Yūichirō Hyakuya

Yūichirō Hyakuya 「百夜 優一郎, Hyakuya Yūichirō」 is the main protagonist of the Seraph of the End: Vampire Reign series. He is a member of the Japanese Imperial Demon Army as well as Shinoa Hīragi's squad in the Moon Demon Company. He, along with Mikaela Hyakuya and a few others, possesses the "seraph" gene, which is relevant to the forbidden taboo and the focal point of the story, "Seraph of the End."

He also appears in Seraph of the End: Guren Ichinose: Catastrophe at Sixteen and Seraph of the End: The Story of the Vampire Michaela.

Human
Yūichirō has medium length black hair which can be considered quite neat and messy at the same time. He possesses sharp green eyes which fall under his thick eyebrows. His eyes are large compared to most other male characters in the series.

As lifestock, he wears the standard white uniform with short sleeves and a hood.

In chapter 2 of Vampire Reign when he is sent to school for his behavior, he is shown wearing his school uniform, gakuran with a standing collar that is black with teal trim. The collar and the top buttons of the jacket are unbuttoned, revealing is a white shirt underneath.

As a private of the Demon Army, he wears the standard JIDA uniform which consists of a long-sleeved black coat with light green details including the shoulder epaulettes which has a brown Sam Browne belt passing diagonally over his right shoulder and two rows of gold buttons on the front. Along with that, he wears a pair of white gloves and a white web belt with a gold waist-plate. He also wears the uniform trousers and black boots which go over the trouser's leggings. Yu keeps his sword on the left side of his hip. Sometimes he can be seen wearing the JIDA hat, and often wears the JIDA cape as well.

He wears a standard demon sword until he is advanced into the Moon Demon Company.

Demon
Yu appears the same as before, but his green eyes are now scarlet. Two black horns appear from his head. His teeth have also become pointed.

Human
Yu is brave, fearless and somewhat reckless, which was shown when he attacked a Horseman while ignoring orders. It is noted that this wasn't the first time. Yu is often called an idiot by those who know him. He is a very narrow-minded person, whose only goal is to annihilate all vampires because of what they did to his "family," and he will overcome any type of challenge in order to accomplish it. He swore to exterminate all vampires for killing Mika.

Despite this, he has a soft spot and worries about his friends first and his goals second. Ferid Bathory considers this attitude to be "cute". Because of this, he empathizes with others who put their family first, as seen when a civilian girl gave his squad false information because vampires are holding her family hostage. After learning why she deceived them, he tells the girl that she did the right thing to save her family. He feels guilty for abandoning Mika and has nightmares about Mika's death for four years until he makes friends with Shinoa and Yoichi. After learning Mika is alive, Yu's personality changes in response and he grows more mature, as noted by Shinoa. He puts more effort into being patient and calm and making friends, and immediately amends his worldview to include Mika even though he is a vampire. His dream of wiping out vampires takes second place to reclaiming Mika. Regardless, even though his best friend is now a vampire, Yu still slaughters them without mercy or hesitation. After Shinjuku, he becomes closer to his squad members and makes Guren promise to help him take Mika back under the promise that Mika will be useful to him, as he comes from the same orphanage as Yu. Additionally, friendship and bonds become more important to him, as shown in a mental battle against Asuramaru, to gain more power or else lose his body, he calls Asuramaru his friend and convinces Asuramaru to yield to him.

Rather than revenge, his primary goal changes to protecting his new "family," in order to avoid a repeat of past events. In Nagoya, he surprises Narumi's squad by memorizing all of their names and promising to protect them.

Similarly to how vampires do not bother to remember human faces and only think of them as "humans" or "livestock," Yu only sees vampires as "vampires" or "bloodsuckers" without bothering to remember their names or faces. He does not even recall the name of his vampire target in Nagoya. The only exception to this rule is Mikaela Hyakuya, and seems to recognize Ferid Bathory.

Seraph of the End
During his first transformation, he goes berserk and attempts to kill any human nearby. He displays no interest in vampires and recognizes no one. He also mutters that sinners must die, and he must kill all sinners.

Upon his second transformation, he curses the tainted humans and plans to turn them into "pillars of salt."

Namanari
In Yu's demon form, he acts like a standard demon. He wants to kill and destroy anyone nearby and screams and rages about being restrained. He even attempts to seduce Mika with his blood and promises to run away with him if only Mika will set him free.

Thanks to Shinoa and Mitsuba's restraints, he has been unable to act on his desires.

When he returns to human form, he does not recall any of his actions as a demon. Despite this, he appears utterly nonplussed about losing his humanity, much to Mika's distress.

History
Yūichirō Amane was born in 2004. During his childhood, both of his parents screamed that he was a demon spawn. Yu's father tried to kill him. His father screamed that he had to kill the seraph of the end now or else the world would be ruined. His mother also goes mad and tries to burn their apartment down with Yu inside, but he is saved by Saito of the Brotherhood of a Thousand Nights. His mother screams about killing the demon before she covers herself with a flammable fluid and sets herself on fire, burning herself to death and committing suicide.

The Brotherhood, later called the Hyakuya Sect, then use Yu in experiments and erase his memory of them. On the day of the Apocalypse, Saito brings Yu to one of the orphanages and leaves him in Mika's care.

Book 3
In chapter 3, the 6 p.m. news shows the fire at an apartment complex. A disheveled woman in her mid-twenties with long, silky black hair steps out of the crowd and screams for Yūichirō. She screams about a demon and says the fire should never be put out. She says the demon child should be killed immediately. She lights herself on fire, and firefighters tackle her.

Saitō from the Thousand Nights appears and approaches the camera before the footage is cut.

Book 5
Mahiru visits Yu, who is being experimented on and abused by the Hyakuya Sect. She asks him about his reason to live and if he has no right to live if he is a demon. Yu does not know how to answer. Since his mind has not broken from his experiences, she tells him he will find an answer one day. A researcher says he will erase all memory of this conversation from Yu’s mind. She asks about receiving one of the Hyakuya orphans to experiment on with cursed gear.

Book 1
In Sanguinem in 2016, Mika donates his blood, cringing as the needle pierces his neck. He chats with Yu, who is sitting next to him. Mika thinks Yu is kind because he always maintains the children's hope about defeating vampires.

Once they finish up and leave, Yu asks him what is wrong and says Mika is spacing out. Mika only says he feels tired after donating blood. Yu prattles on about killing vampires again before telling Mika to not carry everything on his own shoulders. Mika knows that one wrong move will get him killed, and he cannot risk Yu dying. If they both died, then who would take care of the younger children?

Mika tells him not to worry and asks what Yu's surname is, but Yu cannot remember. Yu asks Mika about his family since he does not look Japanese. Mika's mother was Japanese but his father was Russian. Mika says his last name was Shindō. Mika says all of the orphans use the surname Hyakuya because they are all family.

Mika sees Ferid's mansion and splits off from Yu.

Prologue
Yu was taken to the Hyakuya Orphanage in Tokyo on Christmas Day in the year 2012, and told he could meet friends who were just as unwanted as he was. He met Mikaela and the other orphans. Seeing as the two 8-year-olds were the eldest, Mikaela wanted them to be friends, but Yu rejected him. Mika asked if Yu was challenging him to a fight and said he was the leader. They fought, and Mika gave him a serious smack-down. Afterwards, he told Yu that he used to be alone like him, but now he had a big family. And from that day onward, Yu had one too. Yu told him about his parents' violent behavior, saying that "family" no longer meant anything to him. Mika smiled, saying that both of his parents abused him until they got sick of him and threw him out of a moving car. The orphanage took him in after that. The other children shouted out their stories, saying that they never met their parents, their parents committed suicide, or their parents left them at the orphanage door. Mikaela then told Yu that they weren't lonely because that day was the day their new big brother Yu joined them. Shortly after, the director suddenly began to bleed from her nose and mouth and collapsed to the ground.

The adults perished, and Third Progenitor Krul Tepes led the vampire invasion on Tokyo. For the next four years, the orphans survived as livestock for the vampires in the vampire capital of Sanguinem, which is located under Kyoto.

Yu and Mika encountered Ferid, who invites them to his house to partake of their blood, but Mika agrees to go while declining politely for Yu, claiming Yu to be "shy". After Mikaela steals a gun and a map of the underground, they made a daring escape attempt with their orphanage family. Unfortunately, this was all a trap set by a seventh progenitor named Ferid Bathory, who had relations with Mika. Ferid slaughtered the other children in front of Yu and Mika. Yu managed to shoot Ferid in the head, but Mika was fatally wounded. Yu called Mika "family" for the first time. He refused to leave Mika behind until Mika yelled at him and pushed him away. Yu escaped, leaving Mika behind; an action that haunted him for years afterward. After reaching the outside world and realizing the vampires lied about the world's destruction, Guren Ichinose of the Japanese Imperial Demon Army finds him.

Guren mentioned a prophecy and knew that Yu was one of the lab rats from the Hyakuya laboratories. He was one of the children that was being experimented on by the Hyakuya Church to create a weapon of mass destruction, as part of the 'Seraph of the End' plan in destroying the world. Guren knew of this beforehand, thanks to intel provided by Mahiru in 2011. In order to take revenge for his family, Yu joined the Japanese Imperial Demon Army as Yūichirō Hyakuya.

Second Shibuya High Arc
Guren agrees to give Yu the power to kill vampires when they first meet, but he does not put Yu in a vampire extermination unit right away. Four years later, Yu is a private of the Japanese Imperial Demon Army. He gets suspended from the army for disobeying orders during an encounter with a Horseman of the Apocalypse, and is thus forced to attend Second Shibuya High in the meantime. When Shinoa Hīragi tells him his suspension will continue until he makes friends, Yu struggles since he has stubbornly rejected forming close relationships since Ferid Bathory slaughtered his family. He insists he does not need any friends. Shinoa gives him a note from Guren specifically written with the orders to make a friend; he promptly wads it up and throws it to the floor.

With a little persuasion from Shinoa, he steps in to save Yoichi Saotome from bullies. Unfortunately, Shinoa tells him his punishment will be extended if he harms any civilians. Yoichi tells him he wants to join the army to get revenge for his sister's death, but Yu tells him to forget the army and that his sister wouldn't want him to avenge her death. An emergency warning goes off, and Yu challenges the escaped vampire assailant, nearly killing her when Guren arrives and ends her life. Yoichi becomes Yu's friend, meaning that Yu actually reached the requirement Guren gave him. In a dream, Yu's orphanage family tells him farewell.

Yu learns that Shinoa has a cursed gear for slaying vampires and wants to take it from her by force. She rapidly relieves him of that notion. Yu, Shinoa, and Yoichi save Yamanaka's friend Yūji. During the fight, Yu makes contact with the myo-o demon but breaks out of the demon's illusion on his own, surprising Shinoa. She agrees to notify Guren.

In chapter 4, Yu meets and fights with Shihō Kimizuki before attending his first class in the Moon Demon Company Barracks. Guren introduces Yu as the idiot and Yoichi as the crybaby. Yu gets paired with Kimizuki for a practice test. When Kimizuki's sister goes into critical condition, Yu punches Kimizuki and convinces him to go see her during the middle of the exam. They become friends and rivals. Shinoa recommends both of them for the Black Demon Series.

Although Yu earns a zero on his spell craft exam, which is supposed to help determine what rank of cursed gear he can receive, Yu is permitted to try for a Black Demon Series weapon along with Yoichi and Kimizuki. He appears to be nearly illiterate since he used no Kanji on his exam and wrote everything phonetically. Yu challenges Asuramaru, earning the demon's power in order to protect everyone, and Asuramaru informs Yu that 1/10th of him is not human. Afterward, Yu talks to a possessed Yoichi and helps him to regain control over his demon Gekkōin.

Shinjuku Arc
In chapter 8, he meets Mitsuba Sangū, who completes their 5-person squad. A Horseman of the Apocalypse chases a young girl. Against Shinoa and Mitsuba's orders, Yu rescues the girl, and a group of vampires attack him. Mitsuba slaps him for his disobedience, but he declares he does not regret his decision. In the following chapter, they use information from the girl to lead an attack against the vampires. Although the vampires seize Mitsuba, Yu's strength shines through, and he rescues her. Even though the girl deceived them, informing the squad that there were only seven vampires instead of nine vampires, Yu tells her she did the right thing to protect her family.

Before they head to Shinjuku, Kimizuki hot wires a hummer. This impresses Yu, who says he had not been in a car since he was little and anyone rarely uses cars in Shibuya since gas is such a precious commodity. Yu attempts to drive and nearly accidentally crashes into his squad members, leading Kimizuki to violently remove him from the vehicle. Kimizuki promises to teach him how to drive on another date. As they head to Shinjuku, they encounter Thirteenth Progenitor Crowley Eusford. Yu manages to take his right arm momentarily before Crowley is summoned away by Seventh Progenitor Ferid Bathory.

They reach the battlefield in Shinjuku, and Guren summons Shinoa's squad to the 5th Street intersection. After taking his supplement, Yu charges into battle. Enraged over seeing Guren getting stabbed, Yu pierces Mika through the chest with Asuramaru, calling him a bloodsucker and telling him to die. Then, he recognizes his not-quite-dead best friend and family member. Guren grasps Mika's sword with a spell tag and urges Yu to activate his weapon and kill the vampire, but Yu freezes when he realizes who he just stabbed. Mika releases his sword and escapes. Guren hits Yu and asks him why he did not kill that vampire when he had the chance. Yusays that person is Mika, his family. He cries from happiness. steps behind Yu and grabs his shoulder, causing Mika to amputate the responsible appendage. Of course, Ferid says he was just joking about tasting Yu. Mika steps up to Yu and tells him to forget about the humans and run away with him. He lifts Yu and carries him in his arms. Mika warns Yu that Yu is in a bad place and is being used by the humans, but Yu has no idea what he is talking about. Yu struggles and breaks free, jumping to the ground. He says that Mika makes it sound as though he is no longer human and asks if it is his fault. Mika immediately tells him it is not Yu's fault. Mika begs Yu to come with him, insisting that he is Yu's only true friend and the humans are only deceiving and using Yu. Yu looks back when Shinoa screams and sees his comrades defeated by the vampires. When he tries to help them, Mika grabs his wrists and says they have to go. Just then, the special supplement Shinoa gave Yu under Guren's orders takes affect, causing Yu to transform as his seraph component runs wild. Yu screams. Yu swings at Mika and Crowley before moving to kill Shinoa, his true target. Mika jumps in the way, and Yu stabs him through the back. Mika urges Yu against killing humans. He asks Shinoa how she could dare use Yu like that, and the berserk Yu calls Mika a vampire, telling him to not interfere and saying that all humans must be killed. Guren orders Shinoa to embrace Yu to undo the transformation, so she jumps in after Yu flings Mika aside. Yu cries out and hacks up blood before passing out.

Post-Shinjuku Arc
Yu wakes up exhausted a week later.

He looks up books on vampires to try and learn how to turn Mika back into a human. Later, Lieutenant General Kureto Hīragi summons Yu to the Shinjuku Central Army Headquarters First Office where Kureto sicks a starving unarmed vampire on him. Yu kills the vampire without hesitation. Kureto challenges him to a duel but cheats, winning quickly. He then attacks Kureto while his back is turned, but his aide intercepts. He also makes Major General Shinya Hīragi confront Yu. Kureto tortures Yoichi and Kimizuki to try and get information from Yu. He tells Yu about the Hyakuya Sect, asking if Yu was from that family. Yu knows nothing about them.

Guren tells Yu he knew about Yu's connection with the sect all this time, and he agrees to help Yu get Mika back. Shinoa and Mitsuba teach the squad about possession- and materialization-type demons. Yu weakens the curse binding his demon before Kimizuki and faces illusions of his orphanage family and his biological family. After Kimizuki conquers his demon as well, the two spar. Both of them use special abilities, which should be impossible for the possession-type demons they use. Yu uses a technique called "Asura-Kannon," ordering it to fan-out which produces numerous materialized swords.

Shinoa tells Yu about what he really did on the battlefield of Shinjuku, and they agree to side with Guren in the upcoming political power struggle.

Nagoya Arc
They depart for Nagoya. Kimizuki drives the squad down the Tomei Expressway somewhere between Tokyo and Nagoya. Yu leaps out to slay it, and a series of pranks ensue. Kimizuki lets Yu drive the rest of the way to the Ebina rest stop. Shinoa briefs them on their mission.

Yu wanders around the Ebina rest stop. He chats with Yoichi and Kimizuki until Sergeant Makoto Narumi and his squad arrives. The two squads are paired together for this mission. Narumi says he does not trust a bratty kid who showed up late to his first meeting. Yu asks Narumi his age, and he answers nineteen. In response, Yu says he is twenty with a baby face.

Shigure summons Yu for his punishment, and Shinoa and Mitsuba attempt to take responsibility for the squad's tardiness. Yu meets with Guren's squad. Guren is already aware that he is covering for his friends, and he appreciates Yu's development from being so focused on revenge to being loyal to his new family. Shinya and Goshi tease Guren, and Yu asks them if Guren considers his squad family.

Guren tells Yu is here to punish Shinoa. Goshi begins a humiliating illusion of a bound and naked Yu with four tiles piled on his thighs. Goshi makes the illusion Yy cry for forgiveness, help, and his mommy, screaming that he peed his pants.

Shinoa's squad rushes in, and Shinoa quickly orders Shikama Dōji to destroy that illusion.

Guren lectures Shinoa, scolding her that a little mistake could cost her family and squad their lives. He challenges her to a test: Guren, Mito Jūjō, and Shinya Hīragi in a fight against her entire squad. He gives her ten seconds to prepare.

Shinoa assigns Yu and Kimizuki to keep Guren busy. She orders the squad to stay within the radius of her scythe. Kimizuki and Yu do not have time to explain their abilities.

Yu and Guren clash. He manages to hold his own against Guren, impressing the other soldiers. Guren attaches an explosion charm to Yu's head, and Shinoa makes to disenchant it. Jujo stands on her scythe, disabling her movements. Yu charges Guren, and Shinya fires Byakkomaru at him. Guren takes the opening to slip past Yu and breach their lines. He tells Shinoa's squad that it is over, and all their friends are dead.

He introduces them to the other soldiers as 16-year-old rookies and states that three of them bear black demon weapons.

Yu attempts to pick another fight with Narumi, and Mitsuba bashes him over the head. Shinoa apologizes for him. Shinoa's squad agrees that they desperately need to work on their teamwork, and the operation commences. The squads mobilize and head to Nagoya.

Within Lucal Wesker's ward in Nagoya, Narumi and Shinoa's squads have ten minutes left before beginning their assignment. Their target is Fifteenth Progenitor Lucal Wesker.

Although Yu fails to recall their target's name correctly, he lists the name of every soldier on the two squads, promising to let none of them die.

On the ground, Yu acts as point for the squads and charges Lucal Wesker.

Kimizuki, Shinoa, and Narumi jump in. Lucal swings Shinoa in Narumi's path, but Yu defends her. While Yu's back is bared, Lucal claims Yu is too powerful for a human and makes to attack him. Mitsuba summons Tenjiryū's dummies to defend Yu, but Lucal banishes them with a wave of his hand. Kimizuki strikes, but Lucal disarms him. Rika manages to make the first successful attack against Lucal by stabbing him with her weapon from behind. Shusaku summons his demon Akahebi, which becomes a chain binding Lucal's left arm.

By cutting off his own arm, Lucal avoids Kimizuki, Yu, and Narumi's attacks against him.

Kimizuki taunts the vampire, asking if a vampire can regrow his arm if it is vaporized with a curse. He tells Lucal to beg for it if he wants it back, sending the vampire into a rage. Lucal charges in, swatting away Shinoa and Mitsuba's attacks. Yoichi and Shinya fire at him. As he dodges, Yu strikes, slicing the vampire in half. Narumi finishes him. The two squads cheer.

On the streets of Nagoya, Shinoa Squad and Narumi Squad wait for the survivors to regroup. Sergeant Aiko Aihara arrives with a bruised, battered, and bleeding face. Kimizuki notes that Aiko Aihara's squad only has seven survivors, so eight of them died. Yu offers to have his squad take watch while hers rests, and she takes him up on it. Guren and his squad come above ground, but they are all worse for the wear. Narumi reports that Shinoa Squad did very well.

Guren orders Shinoa Squad and Narumi Squad to join his squad and hunt down Crowley, Chess, and Horn. Guren orders them to stage an attack on Crowley that will last ten minutes. If they cannot kill him during that time, they will retreat and tackle the next mission with those numbers. Guren orders Aiko to hold position for thirty minutes and pass on orders to any late teams to report to Nagoya Airport. Anyone late is presumed dead.

Once they reach Nagoya City Hall, Guren looks at the hostages being used through a telescope and knows that they are being used as bait to lure them. Yu insists on bursting in and saving them. Narumi dismisses it as too dangerous and when Yu asks him what they should do, Narumi asks Guren what they should do. Guren suggests that they snipe them from their position and see if they can lure them out but says that if there are too many of them, they are to abandon the hostages and run. Yu shouts that they can't do that.

Shinoa interrupts Yu and asks Guren what their priorities are. In order, he says that their top priority is to maintain their numbers, letting no one die. Their second priority is to free the hostages and lastly, getting the hostages out alive. Narumi states that this is because they are needed for another mission after this. Guren then says that they need to keep the vampires occupied in Aichi Prefecture for as long as they can so they can buy enough time for the main forces in Shibuya to get prepared.

After Crowley catches Gekkōin, Guren and his squad discuss what to do. After careful planning, Guren decides that his squad will take his squad to attack Crowley while Shinoa and Narumi Squads free the hostages. He gives them five minutes to rescue as many hostages as they can and act as a proper diversion for the main force in Shinjuku. As soon as the five minutes are up everyone has orders to retreat to the Nagoya Airport immediately.

Sometime later, Yoichi reports on the situation with Guren's squad to the squad and Yu insists on rescuing him. Shinoa agrees with him but says they only have five minutes. She gives them specific instructions regarding their plan.

Yu breaks through the floor and attacks Crowley. Crowley blocks easily and moves to decapitate Yu. Kimizuki parries the attack, and Mitsuba distracts Crowley by summoning dummies with Tenjiryū. Yu uses Asura Kannon, but Chess and Horn immediately step in and defend Crowley from it. Chess and Horn counterattack and rip apart the shield Mitsuba forms with Tenjiryū.

Guren orders Shinoa Squad to leave. Crowley recognizes Yu as the one who went berserk in Shinjuku.

When Yu moves to rescue Guren, who is on the ground behind Crowley, Shinya stops him and orders him to abandon Guren. Shinoa says their five minutes are up and orders a retreat.

Outside, Yu breaks free of Kimizuki's grasp and complains about leaving Guren behind. Yu asks if ignoring feelings and abandoning family is acceptable as long as it is for their mission. He holds back tears and states that would mean giving up on family. He calls Guren family.

Yu recalls four years ago after Guren picked him up from Sanguinem. One of Guren's men reported that Yu woke up screaming, and Guren comes to check up on him. Yu cries in his bed. Guren asks about what dream Yu had, and Yu says its the same one he always has: Ferid Bathory slaughtering his family. Guren asks if this means he wet the bed again, and Yu snaps, stating that he ever wet the bed. Guren says he will stay there until Yu falls asleep. He sits by Yu's bed and reads documents on the Seraph of the End project begun by the Hyakuya Sect. He stays there from 2:20 a.m. until 2:50 a.m. Yu says he has never really had a family since he was born because his parents called him demon spawn and tried to kill him. He says he made a new family, which was killed anyway. He says that living is painful and wants to know if it is even worth it.

Guren states that living hurts him, too. He says he failed to save the one he loved most, but, if he sticks around, then a day may come where someone needs him. He instructs Yu to live until he finds a new reason for life and people who need him. He leaves Yu and orders him to sleep.

In the present, Yu wipes away his tears and states he cannot follow orders. He says he is not cut out for teamwork. He tells the others to proceed without him, and he will stay behind. He says he would rather die than be unable to save his family. Before anyone can stop him, he swallows two curse stimulant pills for a total of three since the beginning of the mission. Shinoa orders him to spit them up, but Yu begins to cough blood. The curse power overwhelms him, forcing blood out of his eyes and making him scream.

Yu coughs up blood after overdosing on pills to increase his power at the end of the previous chapter. Inside his mind, Asuramaru, calling him hopeless, comments on how Yu appeared to give up on revenge and then became obsessed with living and family. He asks Yu if he wants power that badly. Yu says he does need power to save Guren. He begs Asuramaru to give him power.

Asuramaru says yes. If Yu wants power, he’ll give him all he asks for and more since he feeds on ugly human emotions like obsession and greed. However he complains that the pills Yu took before are a problem as they force the curse to go crazy while keeping his greed in check. Asuramaru says that the contradiction won’t do. He states that Yu cannot expect to just take drugs and get stronger without any consequences so Yu asks how he can get stronger.

Asuramaru says he can’t answer that as Yu is already dead. He says that it was a quick death. Yu took so much of the drug that all his internal organs ruptured and his heart exploded. He says while he has powerful regenerative abilities, but that kind of damage is beyond him. He says Yu’s done. Dead. Then, he amends his statement, saying that at least he should be.

The only reason he isn’t is because of those disgusting angels. Their power is forcibly keeping him alive. They peer into the background of Yu's mind and see something lying on the ground. Yu asks Asuramaru what it is. He says he doesn’t know but from there it looks like a trumpet. Yu has the urge to take the trumpet, but Asuramaru warns him not to take it and insists that Yu take him instead since angels can be far nastier than demons.

Asuramaru notices that Yu’s heart has starting beating again and says that now that it’s fixed, he can take care of the rest. He stabs into Yu's abdomen, telling him not to go with the trumpeters and instead stay with him, accept him. He tells Yu that he can heal him but when he tries to he says that he cannot return Yu to normal. He complains that Yu lost even more of his humanity than before and has become even uglier. Asuramaru orders him to never do that again and claims Yu's body is his. Yu says he does not care and demands for Asuramaru's power. Asuramaru calls him a greedy little human wretch and tells Yu that he has already given it to him as three pills worth of the drug is in effect. He can use all his strength for the next two to three minutes without becoming a demon. Asuramaru then tells Yu to awaken.

Yu wakes up to his friends' panicked faces. He says he is okay and has something to do. With immense speed and power, he leaps from the ground and breaks through the wall to reach Crowley and attacks him. He demands that Crowley give Guren back, and Crowley wonders if he is really human. The two fight, and Crowley delights in the fact he may have to use both hands for once.

Guren, whose wrists have been bound, gets between them and orders Yu to leave. When Yu asks why he is still not strong enough, Crowley answers that it is because Yu is only livestock and asks if Yu fears cows and pigs revolting someday. He insists vampires will never fear humans. Yu repeatedly yells at him to shut up and die, and they exchange blows. Guren orders Yu to stop. He says that Yu's demon will take over if he uses more power than that. Yu refuses to leave.

Crowley mutters that he is beginning to get bored and decides to kill Yu. Guren tells Yu that he has a plan, but Yu needs to leave. Yu does not listens and demands even more power from Asuramaru.

Asuramaru is delighted to help, especially now that the protection from the drug has completely worn away. Yu's desires overwhelm him, and half of his face darkens and a horn sprouts from his head as he becomes a demon. Yu enjoys the power. Crowley says that Ferid always makes interesting things happen. He says that Yu is so lively and full of energy that he wants Yu's blood now and mentions he may drink Yu dry the next time he gets close.

Yu challenges Crowley again. He hears telling Kiseki-Ō to begin the count to nine until the devil's coffin opens. After Kiseki-Ō gets to four, Yu invites Kimizuki to kill this bloodsucker together, but Kimizuki notices Yu's horn. Guren warns Kimizuki that Yu has been possessed and to grab him and run. Yu tells Guren to shut up now that he has the power to rescue him.

Kimizuki tells Yu that that what he said before was right. In this screwed up world, there's no point to living if you don't have a family to cling to. He then says that's why it's his turn to rescue him. Kiseki-Ō finishes the countdown and captures Yu with the devil's coffin.

Kimizuki joins with the rest of their squad while Kiseki-Ō begs to kill Yu, who is in his coffin. Kimizuki orders him to only knock out the demon inside of Yu.He orders Kiseki-Ō to spit him out and catches Yu in his arms.

As Mika engages the Moon Demon Company, he sees Yu being carried by Kimizuki. Yoichi recognizes Mika and asks his group if that vampire is Yu's family.

Shinoa calls out to Mika to identify him, but he tells her to shut up and return Yu to him. Shiho Kimizuki says the should stop him before Mika kills them. Yoichi protests. Mika reaches for Yu. Mitsuba tries to block him, but Mika smacks her axe away. Kimizuki drops Yu while trying to block Mika and says Mika cannot have Yu. Mika throws him aside. Mika begins to lift Yu from the ground, but Yoichi jumps on his back. He says he is not letting Mika go anywhere, and Mika tells him to quit getting in his way. Yoichi says Mika can kill him, but Mika is their family so long as he is Yu's family. Mika knocks him off as well, telling him to not be stupid and to die.

Shinoa activates Shikama Dōji and knocks Shinya away from Mika, surprising both of them. With her back to Mika, she explains that Yu would be mad at them if Mika were to die. She orders Mika to take Yu and run.

Mika comments that family does not exist in this messed-up world. He recalls playing with his own family on the streets of Sanguinem and pulls Yuclose to him. Shinoa tells Mika to hurry up and then meet up with them at Nagoya Airport. Mika asks her why he would meet up with them, but she says she decided to trust him and that is that. Her squad charges at the Moon Demon Company while Mika flees with Yu.

While escaping, Mika holds the unconscious Yu in his arms and pleads for him to wake up.

He eventually crumples to the ground since he lost too much blood when the Moon Demon Company attacked him in the previous chapter. He begs Yu to wake up, stating he must tell Yu something while he is still alive and sane.

Mika takes Yu into a ruined convenience store and tries to make Yu regain consciousness. A child makes a sound down an isle, and Mika attacks him. He says drinking just a little blood would give him the strength to wait for Yu. The child screams for his friends to help him, but they flee and leave him behind. When the child calls him a monster, Mika releases him and slumps to the ground. The child screams and runs away. Mika apologizes to the unconscious Yu, saying that he does not want to become a vampire and cannot make himself drink blood even with Yu there.

In Yu's mind, Asuramaru approaches him. He says that he is really starting to like Yu and praises Yu's honesty about his desire. He says that Yu is broken and does not distinguish between good and evil when it comes to protecting his family.

Yu asks Asuramaru about what happened, but Asuramaru says he only knows what he saw through Yu's eyes. He offers power to Yu, but Yu turns down his offer this time. Asuramaru says Yu's friends are weaklings who will only drag him down and weaken him again. Yu says everything will work out as long as he is with his friends. They argue, and Asuramaru says he will fail no matter how hard he tries. Yu says he is going to work with his friends to save Guren, but Asuramaru asks about the other family member who came to visit Yu today. Yu wakes up.

He hears panting at the other end of the isle and sees Mika. He calls out to him. Mika mutters about human blood and attacks him, not able to recognize Yu and throwing him to the ground. He calls Yu a human and tells him not to resist. He screams about he pain and begs for blood. Yu stares at him, confused. He tells Mika to drink his blood.

Mika jumps on top of him, pinning him to the ground. As Mika is about to bite him, Yu apologizes for having left Mika behind. Mika snaps out of his bloodlust and quickly moves away from Yu.

Yu asks him about his thirst and says its his fault for leaving Mika behind. Mika says he already told Yu it was not Yu's fault. Yu begins crawling toward Mika, but Mika tells him to stay back. He does not want to drink blood, but Yu wants to alleviate Mika's suffering. Mika says to not worry about it and says there is something he must tell Yu.

Yu grabs onto Mika and says he does not care. He says that Mika looks like he is about to die and asks if drinking blood will heal him. He offers his blood for a second time, pulling open his shirt collar. Mika tells him to stop, saying that Yu is making it difficult to resist. Yu focuses only on what he has to do to save Mika and says he does not want to watch Mika die again.

Mika says he has yet to drink human blood since he will not be able to turn back and will forever be an immortal and ageless vampire. Yu turns the words around and asks if drinking his blood means Mika will not die.

Yu asks Mika for a favor, but Mika rejects him before Yu can even say what that favor is. They argue. Yu finds it acceptable to turn Mika into a true vampire, but Mika says he refuses to become a monster. Yu says that Mika should live for his sake, even if he has to crawl through the mud to do it.

Tired of this conversation, Mika says there is something he must tell Yu. Yu responds by covering his ears and saying he cannot hear him. He says he will only listen if Mika drinks his blood first.

Yu takes some broken glass and cuts open his wrist. He refuses to let Mika die. Mika calls him a jerk, and Yu says he is the one who took that cruel jerk and told him he was family. Mika calls him the worst and says it will be his fault for becoming a monster. Yu says that drinking a little blood is not enough to turn Mika into a monster. He says they are still family, no matter what Mika is. Mika begins crying.

Yu offers his blood for the third time, holding out his bleeding wrist. Mika tackles him in a hug and bites into his neck. Yu welcomes Mika home.

After drinking, Mika apologizes. Yu says it did not hurt much. Then, Yu notices Mika's eyes change color. Mika blames Yu for turning him into a monster, so Yu tells him to growl or something then. Mika says surviving by drinking blood from his own family is not normal, and he is a failure as a human. Yu says he is fine if he is not normal. He says Guren took him in and told him to live, even if his only reason was for revenge. Guren said Yu might find someone who would need him again, and he found Mika.

Yu says he does not care if Mika is a vampire now, and he will find a way to change Mika back if Mika ever gets sick of it. He tells Mika to never try to go off and die again.

Mika states that he is the one who is supposed to save Yu and comments that Yu is stronger than he used to be. Mika laughs.

Mika says Guren is probably just using Yu, but Yu says he does not care if either Guren or Mika want to use him. Mika sees this as too risky and says he will never use Yu. Yu points out that Mika just drank his blood. He says Mika may drink however much he needs in exchange for helping him rescue his new family.

Mika warns him against the Demon Army and draws his sword against Yu when Yu insists on finding his family. Yu states he wants to rescue his family, and Mika is obligated to help him. He says he would rather die than be unable to save his family. Mika reveals that the girl with the scythe saved them, and Mika agrees to save only those four.

Yu volunteers to drive to meet with them, but Mika decides to drive instead.

Mika informs Yu about the Seraph of the End Project, the Hyakuya Orphanage, and how the Demon Army is now redoing the same experiment which caused the end of the world eight years ago. Mika invites Yu to run away with him, and Yu agrees to talk it over with the others since Mika is so set on them. He tells Mika that Mika can trust the others as much as he trusts Yu. Mika says he does not see that happening.

Mika and Yu continue to drive to Nagoya Airport, and Mika once again tries to talk Yu out of it. Mika states that the human named Shinoa is no friend of his. Yu retorts that they have already settled the matter, but Mika says he does not realize how terrible humans can be. Yu reminds Mika that Yu is a human.

Mika says he went overseas a few times to destroy human cults who were experimenting on the Seraph of the End. A flashback shows an emaciated Seraph child with wings for arms confined in fluid with an oxygen mask. It begs Mika to kill it, to "kill this ugly thing I've become."

In the present, Mika states that the Demon Army is the worst of them by far. Yu asks Mika what they should do as an alternative, and Mika they should get away from the Demon Army. Humans across the globe are after the Seraph of the End experiment, and experimental subjects like them would only cause trouble for Shinoa.

Yu agrees and wants to at least check on Shinoa and the others from afar. After that, he and Mika will take off. If Yu's friends are safe, then they can plan how to rescue Guren. Mika immediately turns the suggestion down but soon gives in when Yu begs. He says he may be able to do something if Guren is still alive. Overjoyed, Yu repeatedly asks Mika how until he annoys Mika enough for Mika to tell him to shut up. Mika says Yu has not changed since they were children. Mika says the vampire queen kept him as a pet of sorts, and they can ask her for help. When Yu asks if she can be trusted, Mika says she does not know but will at least listen to them. Yu asks Mika who she is to him, and Mika says she is the one who saved his life. On that note, Yu immediately says they can trust her.

Mika asks if Yu has any brain cells in his head at all, and Yu says it was only thanks to her that they could see each other again.

He reappears at the end of Chapter 39, just in time to save Shinoa from Kureto's attack.

He and Mika step into the fray, surprising Shinoa Squad and Narumi. Mika points out that humans are killing humans and tells Yu they should not have come there, but Yu disagrees. Yu asks Shinoa for orders. She issues a retreat. The survivors all request to be backup for the rear guard, but Mika says he can block chains at that speed on his own. Yu chides Mika on teamwork. When Mika asks Yu if he expects him to trust humanity after seeing them sacrifice their own soldiers like that, Yu says that he is only telling Mika to trust him.

Kureto notes that three of the surviving soldiers are Guren's soldiers with the black demons. Chains erupt out of one of the trucks. Mika, Yu, and Kimizuki block them. Kureto says the black demon wielders have matured and muses having them for himself but says that their owner will dispose of them.

An army of vampires arrive, cursing the insolent humans for their recent attack.

The vampires and humans wage war. Shinya shoots vampires near Yoichi and says he and Ichinose Squad will back up the children. He orders them to run. Fighting through their enemies, the children flee. Kimizuki warns Yu that he has run too far ahead.

Guren walks onto the battlefield, sword in his hand. Yu is delighted, and the surviving Moon Demon Company members are shocked. Guren greets Yu and suddenly swings his sword at him. Mika intercepts it, surprising Yu. Guren tells Mika that he is in the way.

Kureto announces to Guren that it is time to begin.

Guren raises up his sword, and chains wrap around his arm as the curse consumes him. Mika tells Yu to run and says Guren has betrayed them. Yu disagrees. Shinoa also tells them to run since Guren is not acting like himself.

After Guren stabs Kimizuki from behind, Yu races to Guren and swings his sword at him but hesitates. Guren calls Yu a "little wuss" and asks why he stopped. Yu cannot believe what is happening and wants Guren to explain himself. He asks if they were Guren's family. Tears escape Guren's eyes, and he whispers to Yu to please run. Relieved, Yu smiles until Guren swings his sword down and deeply wounds him.

Yu collapses, gasping for air as blood drips out of his mouth. His wounds are too deep.

Mika carries Yu in his arms, and Krul is waiting for them. Although Yu is hurt, she says he will heal once he drinks her blood. She holds a hand out to Mika and says it is time they left. Mika glances back at the struggling Shinoa Squad and Narumi.

Yu tells Mika that Guren was crying. He says they have to save him. Mika insists he is Yu's only family. When Yu begins to disagree again, he appears face to face with Asuramaru within his mind. The trumpet from before rests between them. Asuramaru scolds Yu for being so greedy and says he does not have enough power to give them. He calls Yu a traitor and says Yu is betraying him by taking up that trumpet. He says that is the worst decision he could make and says that will erase what is left of Yu's humanity.

Yu answers that he does not really care as long as he can protect his family. He blows into the trumpet and is consumed by a massive power that splits the clouds.

Continuing from the previous chapter, Yu violently awakens into his seraph form but now has two wings instead of only one. Krul says this is bad, and Mika asks how he can save Yu. Shinoa asks what is going on, and Yoichi identifies Yu in the pillar of flame. He reports that Yu is going berserk again. Mitsuba helps Shiho walk, and he begs for Yu to save his sister. Kureto asks about Yu, and a soldier reports that he is an unknown Seraph of the End currently activating within that pillar of fire.

Kureto orders Aoi to crush the second seraph. She commands all units to concentrate on the pillar surrounding Yu. She tells them to aim Abaddon at it.

Mirai twitches and then flies toward Yu. Abaddon fires a blast at Yu, and Yu flies out of the way.

Yu states that the end has come. He says the tainted humans who dare reach for the forbidden now shall become pillars of salt. He raises a barricade of earth before him as Kureto orders a second attack from Abaddon. Yu's barricade successfully blocks the attack.

A soldier reveals that Yu has the second trumpet and is the King of Salt. Aoi worries that Yu could kill Mirai, but Kureto says they do not have a choice. He orders them to kill the trumpet.

Yu manifests a sword in his right hand and slices the manifestation of Abaddon in half. Yu reports that the end has come as he lets the manifested sword dissolve.

Asuramaru appears in front of him. He tells Yu not to kill the humans since he does not desire human deaths. When Yu asks who Asuramaru is, Asuramaru tells him to be silent and calls him an angel. He says he is not speaking to the angel but rather to Yu. He says he will help Yu control the angel as long as Yu draws his sword. He says that Yu may be able to contain the seraph by becoming a full demon. The seraph within Yu orders Asuramaru to be silent and says that humanity sees its end today. Asuramaru ignores him and tells Yu to let out his greed and desire. He tells him to accept his inner demon.

Yu's left hand slowly begins reaching for his cursed gear. The angel yells at the humans to stop and not reach further into the forbidden.

Yu grabs the cursed gear, and Asuramaru grins with delight. A pair of horns sprout from Yu's head. He shouts that he is going to save his family and stabs himself through the chest with the cursed gear sword.

Yu plummets to the ground and Makoto throws Genbushin to catch him.

After the time skip, Mika checks on Yu, in a building and asks Yu how he is feeling. Yu's wrists are chained to a wall in a barren room, and he has a bowl by his foot. He still has horns and fangs. It's seems that Asuramaru has complete control on Yu's body

Post-Nagoya Arc
Still chained to the wall, he reacts to Mika’s presence and demands to be released. He insists that he’ll kill all of them.

As a demon, he begs Mika to remove his chains. He says he will run away with Mika and offers his blood. When that fails, he yells at Mika and demands he remove the chains. Mika counts to 120 seconds, and Yu's horns disappear. He mutters about turning into a demon again and greets Mika. Mika states he became a demon for two minutes longer than the day before, which he has been doing since the battle at Nagoya. Mika frets and scolds Yu for becoming something inhuman and doing irrevocable harm to himself.

Shinoa states it has been exactly three hours since Yu transformed and greets them. She mentions it has been three days since Mika drank any blood, but Mika tells her he never asked her to be his keeper. Yu offers his blood, but Shinoa says Yu is too weak and has a bottle containing blood from everyone for Mika to drink instead.

Shinoa examines the chains and says the wards for sealing the demon are beginning to crack, so she and Mitsuba will have to repair them again. Mika accuses her of pretending to be Yu's friend and points out that everything that has happened to Yu has been due to an experiment. Yu says that Shinoa did not get directly involved, but Mika says he cannot trust any of them. Mika asks what Guren did to Yu.

Shinoa tells them they are not themselves when they are hungry and suggests they get breakfast. She holds the bottle of blood out to Mika, but he knocks it out of her hand. Mika appears frustrated, and Yu scolds him. Mika says he is not Shinoa's pet, but Yu says that blood belongs to their friends.

A human rushes in and addresses Sergeant Shinoa, asking for her help. The Horsemen are attacking their village. With the exception of Makoto, their group fights four Horsemen. Afterward, the villagers thank them.

Makoto arrives with food he found in a supermarket two kilometers southwest.

Mika watches the villagers eat, and Yu joins him. He returns the bottle of blood to Mika. Yu says Mika does not have to drink that blood and can drink his instead, but Mika says he will drink it. He says the thirst is getting worst and is worried he might drink too much of Yu's blood. Yu asks if he is okay with something besides his blood, and Mika says that at least it was not poisoned. Mika asks if this whole "being friends" thing is part of the experiments. He says they are decent for humans but wonders if it is smart to trust them.

Their group notices that Mika drank their blood and approach him. Yoichi asks if their blood was okay. Mika says it was gross. Shinoa rambles about the pure and sweet blood of a virgin and then asks if unchaste blood got in there before looking at Mitsuba with an aghast expression. Yu, Mika, and Shiho share identical blank expressions.

Shinoa brings up their future plans. Mitsuba summarizes what has been going on. She says that the Japanese Imperial Demon Army will probably hunt them down and kill them, which puts the villagers at risk. They mention they cannot travel overseas because of how acidic and poisonous the blood-red oceans are. Monsters even worse than Horsemen swim in their depths.

They suggest surrendering, and Mika rejects the idea of returning Yu to the army to prevent him from becoming a demon. Makoto tells him to keep his fangy mouth shut unless he has any other options. He says he will save Yu no matter what in order to give his friends' deaths meaning.

Yu suggests meeting up with Guren, but Shinoa vetoes that idea and says they cannot trust him. Makoto tells Mika this is the circle of discussion they are stuck in and asks if he has anything to offer.

Mika says the vampire queen, his sponsor, participated in the Seraph of the End experiments. They may be able to trust her. He says she was captured and he does not know what happened to her, but rescuing her might be their least complicated option. Makoto asks if vampires are less dangerous than the Demon Army, and Mika says yes. Vampires actually care little about humans and are only concerned by power-hungry humans. Makoto agrees and says that describes the Demon Army pretty well. Shiho also agrees with that plan and states he does not trust anyone aside from those standing right there. Mitsuba agrees to the plan, and Shinoa says that the Demon Army is the most dangerous organization in Japan.

Shinoa announces their next objective is to rescue Krul Tepes before Yu becomes a full demon.

Yu asks about the best way to rescue to vampire queen. Mika says Krul was captured by Ferid. Yu recalls that Ferid is the one who split the two of them up and killed the rest of their family. Yu brings up shooting Ferid in the head four years ago, but he then realizes that a gun would not kill a vampire. He mentions that Ferid is probably still alive, but Mika points out that Yu saw him back in Shinjuku. Mika asks if Yu really did not notice Ferid at all, but Yu says he was so overwhelmed to find out that Mika was still alive that he was too busy looking at Mika to see anything else.

Makoto asks them to stop talking over their heads and explain what they were talking about. Shinoa begins to explain that Yu and Mika were held in the vampire capital when they were little, but Yu notices a strange sound. Mika says it is a car engine. Yoichi runs to investigate.

Mika says that a human like Yu should not be able to hear that. Mika asks if the demon's possession is advancing even while Yu is awake. Yu answers that it probably is and says his senses are sharper and that he feels a little stronger. Mika is concerned that Yu is really turning into a demon, but Yu blows it off and says that he can protect everyone better if he is stronger. Mika asks what the point is if Yu loses his humanity, but Yu says Mika can hear the sound, too. Since Mika is not human, Yu says this makes them the same.

Yoichi uses his cursed gear to see Ferid and Crowley's approach. When Shinoa asks why are they coming there, Mika says he does not know but advises their group to have nothing to do with Ferid and company. Yu asks about the villagers, but Kimizuki says the vampires have no reason to target them since their group is the reason they are in danger in the first place.

Yu asks Mika about Ferid's strength, and Mika says he is probably the second most powerful vampire in Japan. Mitsuba asks if he is even more powerful than the red-haired one, who is a thirteenth progenitor. Makoto mentions that stronger vampires have higher progenitor rankings. Yu states that Ferid is a seventh progenitor, alarming the humans.

Yu realizes that Ferid let Yu shoot him and escape to Guren on purpose. Yu considers that Ferid and Guren might have been in cahoots, but Yu pushes that thought away and says that Guren was crying. He recalls Kureto's comment about the Hyakuya Sect orphanages and wonders who is behind it. Since it looks like Kureto was still seeking information about it, Yu believes this was not his plan. He believes Guren could not be behind it either. He thinks about asking Ferid for more information.

Mika realizes Yu is thinking of something dangerous and advises him against it. He mentions going to Ferid's mansion when they were younger and says he still regrets it every day. Yu insists it was not Mika's fault.

Kimizuki pats Yu on the back and tells them to quit talking and focus on running.

Natural Abilities
Yūichirō seems to be an excellent swordsman, as he was trained by Guren himself. This is shown when he killed a Horseman using only a sword.

He is also a "Seraph of the End" hybrid with 1/10th of him being not human; he and his old family were experimented on by the Hyakuya Sect, though he doesn't recall it because the adults erased his memories after each experiment. After he overdoses on the curse supplement after vowing to save Guren from Crowley's merciless hands, his non-human part increases.

Cursed Gear

 * Asuramaru 「阿修羅丸, Ashūramaru, lit. "Perfect Asura"」: Asuramaru is a possession-type demon weapon of the Black Demon Series. It resides inside a black sword that Yūichirō uses. Whilst in use, the blade develops a thick green aura. Like Mahiru Hīragi, he can call upon Asuramaru to fully use its power to attack opponents.
 * Asura-Kannon: A special technique using Asuramaru that materializes dozens of floating swords.

Experimentation

 * Drugging Up: Like other soldiers in the JIDA, Yu takes a supplement to increase his synchronicity with his demon to 150% for 15 minutes. After that time is up, this synchronicity drops to zero. There are numerous unpleasant side-effects, and officers only resort to this as necessary.
 * Seraph of the End: By swallowing a special tablet produced by Guren, Yu can lose his mind and undergo a painful transformation. His left eye turns dark and bleeds while a massive wing-like structure sprouts from his upper left shoulder. Although extremely powerful, he goes berserk and attempts to kill any human nearby. By using the golden trumpet within his consciousness, Yu undergoes a drastic transformation. Both of his sclera are dark with gold irises, the edges of his hair become white and has a single pair of irregular black wings. As a completely awakened Seraph, he is the Second Trumpet referred to as the "King of Salt." His main power consists of turning every living being into pillars of salt. Additionally, he can also create a spear made of salt that can block Abaddon's destruction ray.
 * The Progenitor Council is extremely concerned with his immense power in this form. Guren causes this transformation to end by making Shinoa hug Yu. Yu coughs up blood as the transformation ceases. The drug takes five days to get out of Yu's system, and he spends the total of one week in a coma. Even after that, he feels tired. Yu has no recollection of the events that occur while he is transformed.
 * Anime: The transformation is more extensive. Yu's left eye eventually turns into a black pit, and his right eye becomes red. He attacks both vampires and humans without discrimination while he only wants to kill humans in the anime and orders vampires like Mika to get out of his way. Additionally, his power is demonstrated more in the anime when he swings his sword and creates a plume of black energy the size of a tall building with a ring of light around its base.

Trivia

 * Yūichirō 「優一郎」 translates as "kind first son."
 * Hyakuya 「百夜」 means "hundred nights."
 * Amane 「普」 means "far and wide."
 * Due to Yu's name, it is considered a pun when other characters say Yu is kind (優しい). Kindness is also considered one of Yu's actual primary character traits.
 * He was one of the first characters designed, along with Mikaela and Guren.
 * Yūichirō is the only member of Shinoa's Squad who does not have a known biological sister.
 * In the Michaela light novels, Mika asks Yu what is surname was, but Yu can no longer remember that his name was Yūichirō Amane and solely goes by Yūichirō Hyakuya.
 * When Yu first forms a contract with Asuramaru, it is revealed that 1/10th of him is not human. He becomes even less human in chapter 34 after overdosing on curse stimulant pills. At the end of chapter 40, he chooses to erase his humanity completely.
 * Since he lived in a vampire city for 4 years, Yu is nearly illiterate and only writes phonetically without using any Kanji. Vampires have no need to educate livestock on how to read or write.
 * Mika is the first vampire shown to bite Yu. Yu offers his blood three times before he finally convinces Mika to bite him in chapter 36.
 * At the age of twelve, he was 145 cm tall and weighed 38.2 kg.
 * In the popularity poll, Yu earned 3rd place at 3,536 points.
 * According to the fan book 8.5:
 * Interests: Worrying about Mika / Driving cars
 * Favorite Food: Curry, Shortcake (because the children at the orphanage said they wanted to try birthday cakes)
 * What he looks for in the opposite sex: “Shut up.”
 * According to fan book 108:
 * It's been stated that Yu 's favorite color is blue because it reminds him of the blue sky he saw once he escaped from Sanguinem.
 * Yu's favorite pajamas are yellow.
 * One of Yu's dreams is to drive a fast car.
 * Yu's goal after saving Mika is to eat curry.
 * Yu does about ten push-ups and additional training daily.

Quotes: Guren Ichinose: Catastrophe at Sixteen

 * None yet!

Quotes: Vampire Reign

 * "GAH! I CAN'T TAKE THIS ANYMORE!! It hurts! It makes me dizzy! And I can't stand those blood-suckers looking at me like I'm livestock! What do they think we are? Pigs? Cows? Chickens?! That's why we've gotta start a revolution! You and me, Mika. We'll both get stronger, and then we'll go kill the vampire queen and turn this place into a human kingdom!"--12-year-old Yu to Mika in the streets of Sanguinem, Chapter 1, "The World of Blood Legacy"
 * "Who needs some stupid 'family'? I got sent here because my father tried to kill me. My mom kept ranting and raving about how I was demon spawn. She eventually went nuts and killed herself. So do you get it now? 'Family' doesn't mean anything to me!"--8-year-old Yu to Mika the day Yū arrives to the orphanage, Chapter 1, "The World of Blood Legacy"
 * "Quit trying to shoulder all our burdens by yourself!"--12-year-old Yu to Mika in Sanguinem, Chapter 1 "The World of Blood Legacy"
 * "You're... my family. I... finally found a real family! I can't leave you!"--12-year-old Yu to a fatally injured Mika, Chapter 1, "The World of Blood Legacy"
 * "You aren't Mika. Mika would never tell me to get revenge. He was smart, but he was always stupidly nice to all of us. SO WHO ARE YOU?! HOW DARE YOU PRETEND TO BE MY FAMILY!! I'LL KILL YOU!!"--Yu to a myo-o demon, Chapter 3, "The Demon in Your Heart"
 * "ARE YOU STUPID?! WHO CARES ABOUT POINTS?! THIS IS YOUR FAMILY WE'RE TALKING ABOUT! If they die, then... they're gone for good. You won't ever see them again."--Yu to Shihō Kimizuki when told that Mirai Kimizuki is in critical condition, Chapter 4, "The Worst Pair"
 * "Once I have the power, I'll get revenge for the death of my family. Those bloodsuckers killed Mika, so I'm gonna kill them all!! That's my one and only reason for living."--Yu before first challenging Asuramaru, Chapter 6, "Black Asura"
 * "DAMN IT!! SHUT UP, SHUT UP, SHUT UP!! Just give me your power already!! I... need it!! I need enough power to protect everyone!!"--Yu confessing the truth of his feelings while confronting Asuramaru, Chapter 6, "Black Asura"
 * "I don't ever wanna say I survived because I left someone else to die ever again!!"--Yu to Shinoa's squad when he enters an obvious trap to save a human girl, Chapter 8, "Mitsuba's Squad"
 * "What was it you guys said? We humans are 'ugly'? Trash that would sell out anybody if our family's been taken hostage? Ha! Sounds like you're real familiar with that little ploy. You're right. Humans will do anything for their families. We'll happily lie, cheat, make deals with the devil, or even become demons ourselves. If you wanna call that 'ugly,' then fear human ugliness when it kills you, Bloodsuckers!"--Yu to the enemy vampires in Omotesando Station, Chapter 9, "First Extermination"
 * "...'Those humans' are using me? What's that mean, Mika? You... You make it sound... like you aren't human anymore. It's my fault, isn't it? My fault for running away..."--Yu to Mika when they reunite, Chapter 13, "Reunion of Childhood Friends"
 * "S-s-ssi-sinners... S-sinners must... d-die. M-must kill... all s-si-sinners."--Berserk Yu preparing to kill Shinoa, Chapter 13, "Reunion of Childhood Friends"
 * "Do not interfere, Vampire. All humans must be killed."--Berserk Yū to Mika when Mika protects Shinoa, Chapter 14, "Everyone's a Sinner"
 * "It wasn't a dream. And that means Mika really is alive. Ha ha... He's alive... Ha ha ha... I'm not dreaming... He really didn't die... Thank God... I'm so glad!"--Yu to himself, after waking from a coma, Chapter 15, "Complicated Connections"
 * "Just you wait, Mika. I swear... I'll save you."--Yu to himself, Chapter 15, "Complicated Connections"
 * "...I was looking west. That's where Mika's gotta be, right? In the vampire city. I heard the place they held us was somewhere underneath Kyoto... Someday, I swear... I'll go get him back."--Yu to Shinoa when asked what he was looking at, Chapter 18, "Possessed by Mahiru"
 * "I tried climbing back up using my sword, but some stupid janitor yelled at me for putting holes in the walls!"--Yu after returning from the roof Guren previously flung him from, Chapter 18, "Possessed by Mahiru"
 * "Whatever your reasons, if you hadn't rescued me that day, I would've died. I do still feel like I owe you for that. So what I wanna know is... Am I actually useful to you? That's all. I don't care what you and that Hiragi guy are fighting about. I don't care what you're after. All I want to know is, do you need me? If you do... Would you want Mika, too? He was in the same orphanage as me. If you do... If you think you could need Mika like you need me... Then, I'll be your guinea pig or anything you want. I'll do everything I can to help you with whatever you need. Just tell me how I can get Mika back!"--Yu to Guren, Chapter 18, "Possessed by Mahiru"
 * "Those words don't hurt me anymore. Besides, I don't care if I am demon spawn. If Mika needs me.. If Guren, Shinoa, Mitsuba, Yoichi, and Kimizuki want me as their friend, then I don't care if I'm a demon."--Yu to Asuramaru, Chapter 20, "The Demon's Nightmare"
 * "I don't care if you're a demon. I need you, Asuramaru. Join me, please. We can be friends. Help me rescue Mika... He's family."--Yu to Asuramaru, Chapter 20, "The Demon's Nightmare"
 * "I... Um... This is kinda embarrassing, but... Well... Guren said we're family now, right? So you, Yoichi, Kimizuki, and Mitsuba... We're all a new family. And I've started to feel that's true. You guys are important to me. But... I can't forget Mika. He's also an important family member. See... My parents abandoned me. So maybe I don't really know how families work. But can I ask you guys this?  Just because someone in your family betrays you, does that mean you have to betray them back? I don't... think it works that way. So even if Guren betrays us... and Mika, well... even if he is a vampire now... he's still family. We're all still family, and we always will be."--Yu to Shinoa's squad, Chapter 23, "Ambition in the Demon Army"
 * "LET ME GO!! I said leggo!! What's wrong with you guys?! You can't be serious about leaving Guren behind?!"--Yu after Guren Squad and Shinoa Squad abandon Guren, Chapter 33, "Demon's Lullaby"
 * "So, if it's for the mission... should we have to ignore our feelings and abandon family? But, Shinoa... If we do that... If we just give up on family in this empty, ruined world... Then what? What else is there... to cling to for survival out here? Guren... He... He's our family!! (Pause) Crap. I can't do it. Sorry, Guys. Looks like I'm just not cut out for that teamwork stuff. You all go on ahead. I'm gonna stay here. If I can't save my family... I'd rather die anyway."--Yu to the Shinoa and Guren Squads before overdosing on curse stimulants, Chapter 33, "Demon's Lullaby"
 * "Why'd you save me? I... I don't have a family anymore... I haven't since I was born, really. My parents called me demon spawn and tried to kill me... I made a new family, and then they all got killed too. After all that... What's the point in living? Is it really worth it... for me to even bother?"--12-year-old Yu to Guren in a flashback, Chapter 33, "Demon's Lullaby"
 * "NO!! DON'T YOU DARE GIVE UP!! YOU... YOU WERE THE ONE WHO TOLD ME I HAD TO LIVE DESPITE ALL THE PAIN!! SO BE A DAMN ADULT AND BE A GOOD EXAMPLE FOR ME!!"--Yu to Guren before becoming possessed, Chapter 34, "Asura's Power"
 * "Bwah? Aah..!  So... much... power..."--Yu after becoming possessed, Chapter 34, "Asura's Power"
 * "Mika, whoa! It's me! Yu! Don't you recognize me?!"--Yu to Mika, Chapter 36, "Yu & Mika"
 * "Who cares about that right now?! You look like you're about to die, Mika! What can I do?! How can I help you?! It's blood, right?  Will you heal if you drink some?  Then, go on and drink mine! Here! Take it!"--Yu to Mika, Chapter 36, "Yu & Mika"
 * "Please, Mika! Tell me what I need to do to save you! What do I have to do, Mika? I mean, you're here! I finally found you! But if I have to just sit here and watch you die again... I..."--Yu to Mika, Chapter 36, "Yu & Mika"
 * "Hold on. Back up a sec. If you drink my blood... that means you won't die, right? Hey, Mika? You, uh, mind doing me a favor?"--Yu to Mika, Chapter 36, "Yu & Mika"
 * "If you up and die on me again... I... I'll cry, you moron!!  So live, dammit!  Even if you have to turn into a vampire!  Even if you have to crawl through the mud on your hands and knees--live!!"--Yu to Mika, Chapter 36, "Yu & Mika"
 * "Besides, if you're oh-so-ready to just keel over and die, Mr. Smarty-Pants Blockhead... stop trying to make me feel bad by preaching about how you've never drunk any human blood! If you're gonna die, go crawl in a corner and do it quietly!"--Yu to Mika, Chapter 36, "Yu & Mika"
 * "LA LA LA LA LA!! I can't hear you!! Who's gonna pay attention to some dumb idiot who just gives up on living like that! If you want me to listen, drink my blood first. If you want to save me, then let me save you first. You aren't going to die, Mika. I won't let you."--Yu to Mika, Chapter 36, "Yu & Mika"
 * "Hah! Don't be stupid. Just drinking a little blood isn't enough to make you a monster. No matter what you are, we're still family."--Yu to Mika, Chapter 36, "Yu & Mika"
 * "Welcome home, Mika."--Yu to Mika after Mika bites him, Chapter 36, "Yu & Mika"
 * "Years ago, Guren told me something. Oh! You wouldn't know him. He's the guy who took me in after I escaped on my own. I'd just lost all of my family. I was hurting so bad inside, and I wanted it all to end. I wanted to throw it all away and give up on life. But he told me that, even if my only reason was for revenge, I should live.  So then...  Maybe someday, somewhere... I'd find somebody who would need me again.  So I gave the whole living thing a chance. Even though I figured no one would ever need me, I kept surviving. Struggling, flailing around like a total idiot... But apparently I kept at it long enough that I found you again. Mika... let's live on together, okay?"--Yu to Mika, Chapter 37, "Monsters & Family"
 * "I died long ago on the day my parents abandoned me. But then you helped me live.  And after you, it was Guren.  Somehow, thanks to you two, I'm still here.  And in that case, if either of you want to use me... fine.  Go ahead.  I don't mind."--Yū to Mika, Chapter 37, "Monsters & Family"
 * "I said I wanted to rescue my family. So I'm going to rescue them.  And you're obligated to help me."--Yu to Mika, Chapter 37, "Monsters & Family"
 * "What? Run away to somewhere both the vampires and the Demon Army won't ever find us? Man, that brings back memories. Back then we were both desperate to run away from our world of vampires and slavery. So we escaped... Hoping and praying to find some paradise where we could live in peace... But all we found was this. We can't run, Mika. There's nowhere to run to. No matter where we go, all we'll find is more humans and vampires."--Yu to Mika, Chapter 37, "Monsters & Family"
 * "Yeah, yeah. Say that all you want...  I'm still a human myself, y'know."--Yu to Mika after Mika keeps harping on how terrifying humans are, Chapter 39, "The Beginning of the Plan"
 * "REALLY?! That's awesome!! How? Well? Tell me how... C'mooon! Tell me, tell me, tell me! How're we gonna rescue Guren? Mikaaa!"--Yu to Mika after Mika says he may be able to do something about Guren, Chapter 39, "The Beginning of the Plan"
 * "Well, without her saving you, we never would've seen each other again! It's only right to be thankful to her for that."--Yu to Mika about Krul Tepes, Chapter 39, "The Beginning of the Plan"
 * "Shinoa, I have no idea what's going on here, but we're all gonna help each other get out of this alive. Shinoa, what are our orders?"--Yu to Shinoa, Chapter 40, "Trumpet of the Apocalypse"
 * "Teamwork first, Mika!"--Yu to Mika, Chapter 40, "Trumpet of the Apocalypse"
 * "I swear!! I'm gonna get us all outta here!! And I won't let any of you die!!"--Yu to his squad, Chapter 40, "Trumpet of the Apocalypse"
 * "This... This can't be happening. Tell me this isn't happening, Guren. You'd never betray your friends and family, right?! There has to be a good reason for this!! Say something! Anything!! Guren!! Weren't... Weren't we... Weren't we your family?!"--Yu to Guren, Chapter 40, "Trumpet of the Apocalypse"
 * "Mika... Guren... H-He was crying... We have to save him..."--Yu to Mika, Chapter 40, "Trumpet of the Apocalypse"
 * "As long as I can protect my family, I don't really care."--Yu to Asuramaru when he betrays Asuramaru to pick up the trumpet and lose his humanity altogether, Chapter 40, "Trumpet of the Apocalypse"
 * "The end has come. Tainted humans who dare reach for the forbidden... May you all become... PILLARS OF SALT."--Yu awakened as a seraph, Chapter 41, "Arrogant Love"
 * "The end has come. On this day, the cycle of human greed and desire... shall crumble... as naught but pillars of salt in the wind."--Yu as a seraph, Chapter 41, "Arrogant Love"
 * "SILENCE!! HUMANITY SEES ITS END THIS DAY!!"--Yu as a seraph to Asuramaru, Chapter 41, "Arrogant Love"
 * "STOP!! Cease this, humans!! Do not reach further yet into the forbidden!!"--Yu as a seraph before becoming a demon, Chapter 41, "Arrogant Love"
 * "LET ME GO!! UNCHAIN ME RIGHT NOW!! I'LL KILL YOU!!  I'LL KILL ALL OF YOU!!"--Yu to Mika after becoming a full demon, Chapter 42, "Sanguinem's End"
 * "Please... Mika... Take these chains off of me, wouldja? C'mon. We'll run away together. Just the two of us... You and me... We're the only family we've got. Right? ...Oh, I know! You've got to be getting thirsty, right? You can drink my blood. Then we'll run away together. We'll run away from all the humans... and all the vampires, and go live in peace--just the two of us. Isn't that what you want?  ...C'mon, Mika. They hurt. Really. Take these chains and wards off. Please, Mika.  DIDN'T YOU HEAR ME?! I SAID TAKE THESE DAMN THINGS OFF OF ME!! TAKE THEM OFF!! GET THEM OFF OF ME NOW!! I'LL DEVOUR YOUR ENTIRE SOUL!! (Yu's returns to human form). Buh? Oh. I guess I turned into a demon again. G'morning, Mika!"--Demon Yu to Mika, Chapter 43, "Where It All Begins"
 * "Those 'stupid humans' are all your friends now, y'know."--Yu to Mika, Chapter 43, "Where It All Begins"
 * "Ferid... He's the one who split the two of us up... and... killed Akane and the rest of our family."--Yu to Mika, Chapter 44, "A Drive Along Death's Shoreline"
 * "Ha ha ha... I was just so overwhelmed that you were still alive and all...  I guess I was too busy looking at you to see anything else."--Yu to Mika about why he never noticed Ferid in Shinjuku, Chapter 44, "A Drive Along Death's Shoreline"
 * "I guess that makes us the same!"--Yu to Mika about Yu losing his humanity, Chapter 44, "A Drive Along Death's Shoreline"
 * "Hey, Mika? Do you think Ferid let me escape on purpose?"--Yu to Mika, Chapter 44, "A Drive Along Death's Shoreline"
 * This was planned. All of it.  From the beginning.  Then...  When I got out of the vampire city...  The fact that I came across Guren right away was... No...!  Guren cried.  I saw him crying...!  Is he somehow tangled up in this whole thing, too?  But whose plan is it?  ...So did this plan start before the catastrophe?  In that case, Kureto Hiragi can't be behind it.  He sounded like he was still looking for information about it.  Guren can't be behind it either.  Is it Ferid?  It might be worth talking to him at least once...--Yu's thoughts, Chapter 44, "A Drive Along Death's Shoreline"