Yūichirō Hyakuya/Relationships

Yūichirō Hyakuya was almost killed by his parents before spending time in the Hyakuya Orphanage where he would meet Michaela Hyakuya. Raised in an underground vampire city Yu would escape and learn from Guren Ichinose that humans existed outside. Unwilling to befriend others, he was placed within the education system and aspired to join the Moon Demon Company. He was assigned to Shinoa Hīragi's squad and tasked to undermine vampires. Yu interacts with various other characters throughout the Seraph of the End series, which affects himself and the story. This article details Yu's relationships with other characters.

Step-mother
As a child when his step-mother's apartment goes up in flames, she screams that Yu is a demon and should die. She then douses herself in gasoline and attempts to set herself on fire until firefighters tackle her to the ground. She succeeds in burning herself to death. Saitō later reveals that she was not his biological mother, but was his step-mother, however Yu is unaware of this.

Father
His father believes Yu should die for the good of the world, is willing to stab and kill him to achieve this goal but ends up dead before being able to. This experience had affected Yu, as he cries about it to Mahiru Hīragi while being held captive by the Hyakuya Sect. Asuramaru later uses this memory to terrorize him in a nightmare. Yu felt like he died on the inside when he was treated this way by his parents.

Mikaela Hyakuya
At eight years when Yu was transferred to this orphanage Mika knew they were the same age and was keen to become Yu's best friend, and family in keeping with what the orphanage director taught. Accordingly even though Yu was hostile from his recent experiences and rejected Mika's friendliness, even challenging him to a fight where he was beaten, Yu was still immediately welcomed in the family. Hearing Mika understand how his experiences must have been awful Yu heard Mika's account of his own parental abuse.

After the virus killed the orphanage director and vampires emerged to take custody of the Hyakuya orphans, Mika and Yu looked after the younger orphans, eventually creating Yu's "family." Yu and Mika once discussed what they would do if they left the vampires' city. Yu answered that he would like to go to paradise yet was confused at Mika leaving and saying that he should work hard. Angered at later learning that Mika had been going into seventh progenitor Ferid Bathory's home to offer his blood Yu refused to eat the curry Mika had sent with him knowing how the ingredients were obtained. He stated for Mika to let himself go in his place next time. Yu was the first person Mika shared his escape plan with having stolen a map and gun to help with this. When the escape was revealed as a trap by Ferid, Yu was greatly anguished at Mika's injuries and would not leave him behind. After crying that he finally had a family Yu was pushed away for him to escape. Yu was the only survivor and was haunted by this experience particularly due to him feeling that he ran away and left them after they were slaughtered. Swearing vengeance on the vampires Yu would suffer from nightmares on the experience where the focus was on leaving Mika behind with Ferid. Four years later after Yu joined the Moon Demon Company, he met Mika once more in Shinjuku after stabbing him from behind after seeing that a vampire was trying to kill Guren. However, when Yu realized that it was Mika he stabbed he was in complete shock and confusion. Tearful at seeing him again Yu called to see if it was really him. Surrounded by enemies and with his squad's safety at risk Yu was pressed into retreated back with the Moon Demon Company. Pursued by vampires and separated Yu was picked up and carried away by Mika but rather than hear that he was being used by humans Yu picked up on the words and questioned whether Mika was still human. He asked out of guilt that Mika had been turned into a vampire because he left him. With his squad in danger Yu would not leave them having done that before. Unconscious from his transformation he did not see Mika taken away when the vampires retreated. Afterwards Yu's deeply entrenched hatred of vampires never once entered his mind where Mika was concerned and he was moved to tears that Mika was still alive and vowed to save him no matter what. Yu searched for ways to turn a vampire back into a human and would also request that his squad and then Guren as well help retrieve Mika. It was in Nagoya after a vampire extermination mission that Yu would be found unconscious by Mika. Whilst Mika was severely injured. With help from his squad Yu was allowed to be taken by Mika for them to meet up at the airport later. After Yu woke up, he saw how thirsty Mika was and encouraged him to drink his own. Mika put up a fight against it, protesting all the way through, but he gave up after Yu claimed that he could not live if he watched his family die once more. His methods to persuade Mika to drink was that he would cry otherwise and then expressed skepticism that Mika did not want to live by pointing out that he would have gone off and died elsewhere if he really felt that way. From that angle Yu worked on eroding Mika's reluctance to drink since there was a time limit with Mika weakened. He would only listen to what Mika had to say if he drank his blood and lived. Yu's was the first human blood that Mika drank and he watched Mika's eyes turn from blue to red signaling that he has finally become a true vampire. Yu helped ease Mika's conflicted feeling at his change and said if Mika got tired of being a vampire Yu would find a way to change him back. Largely, Yu emphasized that they promise not to give up on living again. As his friends were in immediate danger Yu turned to Mika for help despite his unwillingness to head back. Just as Mika done with him Yu desired to integrate Mika into a larger family where this one needed protecting. Whilst he encouraged Mika to work as a team when it was clear the Demon Army was set on murdering them Yu would then be defended by Mika when Guren attacked. He would escape the army and vampires with Mika and spend three months near the ocean.

With Mika needing to drink and considering the bottle of squad members blood Yu would discretely place himself beside Mika and mention he could drink his to avoid any troubling feelings Mika may have about drinking blood. He appeared happy that Mika was sharing his thoughts on their next course of action with the team. When outside Ferid's mansion where Fuola Honte began attacking Yu was distressed at Mika being attacked. Inside at viewing the bodies of their deceased orphanage family members Yu was comforted by Mika holding his hand.

"I did find one. I have a reason to live. I have you, Mika."

- Answering Mahiru's question that he did find a reason to live as Yu takes ahold of Mika's arm.

Later, when Mika and Yu are fighting Guren, he meets Mahiru Hīragi again. She asks him if he find a reason of his life and he takes Mika by the hand and says that he is the meaning of his life. Later, when Mika drinks Yu's blood due to his injury, he says that he feels strange.

"I... I don't want to be alone. I don't ever want to feel this bad ever again. I... I just can't do any more than I already have. I wish I could disappear. Vanish forever!"

- After Mika does not come back, Yu processes the situation.

As Mika begins to die and transform into a demon, Yu begins to cry. First, he asks Mika to drink his blood and asks the devil or god to save Mika. When Yu realizes that it is impossible to save Mika, he asks Asuramaru to kill him. Asuramaru says that Yu always considered himself a monster and if there was no one next to him who told him otherwise, then he was "empty inside", but that someone dies, implying that Mika was such a person for Yu. Asuramaru says that Mika loved him and gave his life for him, which makes Yu cry even more and says that he does not want to be alone, implying that it is without Mika that he feels alone. On the official Japanese website, in the description of chapter 90 it was said: "For Yūichirō, who was born without anyone who needed him, and with parents who called him a demon, Mikaela, who loved him, is the meaning of his life. If Mikaela dies, he can no longer live."

"No matter where in the world you are, I'll find you and save you! So wait for me, okay?!"

- With Mika becoming a demon who could kill them Yu leaves with Krul

When Krul comes to Yu, she says that they should leave. Yu doesn't want to leave Mika and Krul tells him that Mika will kill him. Yu doesn't want to believe it, but Krul reminds him that Mika is becoming a demon and if he lets himself die now, he can never save Mika. Realizing that there is a way to save Mika, he begins to obey Krul and promises to save Mika wherever he is.

When Krul asks if he really seriously wants to save Mika, Yu kneels in front of her, begs her to tell her how to save Mika, and says that his life is more important to him than his own. Krul says he has it just as bad, implying that Yu and Mika feelings are the same towards each other.

When Guren says that they are going to turn Mika into a cursed gear and tie him to Yu, Yu is shocked, but then realizes that Guren will save Mika and rejoices.

When Yu realizes that Asuramaru is indeed the enemy and Mika is in danger, he tells Asuramaru that he will not forgive him and will be very mad if he harms Mika. When he sees Mika's sword, he begins to rejoice like a child and thinks Mika is there.

"My Mika."

- About Mika

Later, Yu, for some unknown reason, telepathically hears Mika's voice calling him for help. He starts screaming and asks everyone to hurry up, as Mika is in danger and he will go anywhere to Mika and kill whoever comes between them. When Guren says that Mika does not remember him and will take possession of his body, Yu says that he is not against it, because it means that Mika will live. Yu screams again, grabs Mika sword and vows to save him. When Yu goes to Mika world, he is very angry with Ashera. He says that he will not forgive Ashera for what he did to Mika and exclude him from the family. He also calls him "My Mika".

"I can feel the power inside. Right now, my desires have gone completely berserk. Man. It feels so good... living purely for my desires. Now... let my heart shout that desire aloud... I'm saving Mika."

- Yu about himself

Yūichirō's desire to save Mika reaches such a peak that he begins to go crazy. In one of the dialogues with Asuramaru, he says that his main desire is to save Mika, to which Asuramaru replies that this is a lie and he has another desire. Immediately Asuramaru says that this desire is related to Mika. He asks Yūichirō why he is so fixated on Mika and what desire he has that drives him be so fixated on Mika. But Yūichirō doesn't answer that question. Later, when he reconnects with Mika, he tells him that even if the world ends tomorrow, he will still save him.

After he wakes up in an illusionary world, he remembers that this is where Mika returned to him and rejoices. When he finds a demon, he happily runs to him, but as soon as he realizes that he does not remember him, his expression changes. At first, he wants to let the demon eat him, but remembers Guren's words, so he thinks Mika will cry if he dies. He decides to subdue the demon and fights with him. He again talks about letting his desires run wild in order to save Mika. During the battle, he again recalls Guren's words that the only way to defeat is to break the demon's heart, so Yu decides to do it, although he doesn't want to hurt Mika. When the demon pierces Yu's heart, he sees memories from Sanguinem with Mika dying in Yu's arms as his greatest fear. After Yu pierces Mika's heart, he sees the same fears in his heart and realizes that they have the same dream. When the demon calls him "Yu-chan," Yu is delighted as he thinks Mika remembered him. When Yu realizes that this is not so, he says that he will make a human of Mika again, because they are family, and will save him. When Yu loses and the demon enters his heart, he takes on the form of Teen Mika. This shows that Mika is Yu's greatest desire.

"Mika. Hey, Mika. It's me. Send your mind back to me. If we work together we can get away. Together, we can go anything. It's okay, Mika. Let's do it together. I'll devour you and you devour me. That will let you become my demon."

- Yu in the present calms Mika down and encourages him to become his demon.

While in Yu's heart, Mika realizes that the eye that is looking at him is kind and does not regard Mika as an enemy. When Yu realizes that Mika is in danger due to Shikama's attack, he begins to call him and speak words of support to him. He says "Together" many times and that he and Mika can do everything as long as they are together. At the end, Yu says that he will devour Mika, and Mika will devour him, thereby allowing him to take over him.

Akane Hyakuya
As children, Yu denied the statement when Akane said that they are all apart of the same family. When she died, Yu was very saddened over her death. He was completely enraged and even started to go berserk with his demon once Ferid showed im her decapitated head in a jar. Later in Ferid's mansion, before going downstairs to see the encased corpses of his family, Yu told Yoichi that he would carry Akane's head. Once given to him, he then apologized to her for never calling her "family" and running away. At Guren's mansion, he says that once he brings back Akane and the other children he will tell Akane they are family. That Akane would be brought back is a significant reason why Yu is comfortable with human resurrection regardless of the cost. Yu again reveals that he will resurrect Akane during a conversation with Mika.

Hyakuya Orphanage Family
Whilst he was not interested in the very concept of family at first Yu would become a paternal figure to the Hyakuya orphans as they lived together. Yu would miss them dearly after their passing and be troubled by nightmares of what happened combined with the guilt that he ran away and left them.

Mahiru Hīragi
As a child Yu is visited by Mahiru while he is imprisoned and asked about the meaning of life. Yu at first tells her to go away, but she does not. When Yu explains to her that he is a demon spawn, Mahiru questions why he thinks that, and says he appeared human to her. Before the researchers mess with his memories, Yu is told to stay strong and that one day, she will return to free him from the Hyakuya Sect. Eight years later, after Asuramaru finds this memory deep in his mind, Yu tells Guren that he vaguely remembers her but not her identity. He would sees Mahiru's spirit once she separated from Noya and would remember who she was.

He later learns that Mahiru is Shinoa's sister and the one who created the cursed gear. He listens to Krul's story about the deal between her and Mahiru. They meet when Mahiru arrives with Guren. Despite her actions before, it seems that he does not hate her.

Saitō
He is saved by Saitō from his burning apartment and taken to the Thousand Nights. Yu is dragged to the orphanage that Mika is at on Christmas Day, and told he will meet people just as unwanted as he is.

Shinoa Hīragi
In class Yu finds her as his appointed army surveillance officer. She becomes Yu's first female friend in the army, and he joins her squad later on. Yu eventually gets used to her teasing. After the battle in Shinjuku, Shinoa starts to develop a crush on Yu, but he has yet to realize her feelings. He is able to convince her to help him save Mika, and they hold hands. Yu shows guilt once he learns that he nearly killed Shinoa during his transformation at Shinjuku. He saves Shinoa before Kureto murders her at Nagoya Airport. Shikama Dōji later reveals to Yu that she is in love with him and tries to save her from his grasp, ignoring Asuramaru's warning. He is devastated after seeing her in a comatose state to the point of ignoring his status as a former soldier and offering to be experimented on by Kureto's order, as long as Shinoa is saved.

Later, when Yu and Shinoa reunite, it seems that Yu has no memory of what happened to her earlier, including what Shikama said. Yu is glad to see her like to the rest. When Shinoa and Mitsuba are both severely drunk, Yu puts them on his shoulders. Shinoa blushes a lot and says that he is not obliged to do this, to which he replies that they are all friends, mean that Shinoa is no more than a friend to him. When Shikama takes possession of Shinoa's body and Krul attacks her, Yu is worried about her. When Shinoa wakes up, he rejoices at her return, asks if she is okay and puts his hand on her shoulder. When Shinoa says she will cry if Yu dies, Yu seems to ignore her words. In a flashback, Yu recalls her words that the squad will be waiting for him and she wishes him luck. In response, he smiles.

Yoichi Saotome
Finding Yoichi being bullied Yu would intervene and help him. He discouraged Yoichi from joining the Moon Demon Company due to his gentle nature. Yu would find Yoichi as the one friend he makes during his brief stint of high school, the one who helps him pass Guren's criteria of progressing further. When Yoichi was overcome by his demon with his mind lost Yu was adamantly against dispatching him. Yu threw down his weapon and appealed to Yoichi within to return and refused to inflict harm upon him. Later, they both are admitted to a squad under Shinoa. Like all his other comrades, he treats his friend nicely and is committed to helping him. Yu would be surprised at the swift advancement Yoichi makes with his cursed gear capabilities.

When they are in Osaka and Yoichi sees Lacus, Yu worries about his condition. Later, when they meet after the events in Shibuya, Yu is to glad to see him like to the rest. During the ritual ceremony, he learns that Yoichi also did poorly at school and is happy about it. Later, he pays attention to Yoichi's words that they are his family and do not want anything to happen to him. He and Yoichi, along with Mitsuba and Kimizuki, close up hands.

Shihō Kimizuki
Yu crashes into Kimizuki (literally) on his first day of class for the Moon Demon Company. The two fight often at first and develop a rivalry, but they both have strong family values. He is a tidy person, who is good at cooking. He is a surprisingly caring individual. Yu considers Kimizuki as a comrade who he'd protect and a family member of their group.

When Ferid drinks a lot of Kimizuki blood, Yu worries about him and promises to get him meat. During the battle with the sixth trumpet, he promises that he will save Kimizuki's sister. When they are meet again, he is glad to see him like to the rest. He tells Kimizuki about what happened earlier and they go to fight outside. Yu attacks Kimizuki, but when Kimizuki tells him not to give in to him, Yu becomes more serious. Yu is glad when Kimizuki is getting stronger than before. When Guren arrives again, Kimizuki tells him not to believe him, but Yu ignores Kimizuki words. He later hears Kimizuki say that he must subdue Mika and return alive. He and Kimizuki, along with Mitsuba and Yoichi, close up hands.

Mitsuba Sangū
When she first meets Yūichirō and her new group, she dislikes the idea of working with newbies and working under Shinoa, but she opens up and accepts them as time goes on. She and Yu mutually trust each other, and Yu does not mock her when she gets a promotion despite doing nothing on the battlefield. He says she can use her new authority to help him get Mika. Like the other members of his squad, Yu thinks of her as family. He is not aware of her feelings for him.

When Crowley attacks Mitsuba, he is very worried about her. When they arrive in Shibuya and Aoi is angry with Mitsuba, Yu protects her and says that he is Mitsuba's family, so he won't let anyone harm her. He is happy when Mitsuba thanks him. When Mitsuba is worried that Yu is experimenting on himself, he calms her down and tells her that she should be with Shinoa. Later, when they meet again, Yu is glad to see her like to the rest. When she and Shinoa are very drunk, he lifts them onto his shoulders and says that they are all friends, so he does not care if they vomit on him. Yu is surprised when Mitsuba says he will hit him if he allows Mika to take over his body.

Guren Ichinose
Yūichirō meets Guren when he reaches the outside world. Guren rescues him because he knows Yu is a survivor of the Hyakuya orphanage, and he wants to use Yu to reach his goals. After that, he becomes almost like a father to Yūichirō and teaches him how to survive in that world and use a sword. Even after learning that Guren is experimenting on him, Yu remains loyal to Guren. Yu convinces Guren to help him save Mika. When Crowley captures Guren, Yu gets angry and disobeys orders to save him from the vampire. He acquired his whereabouts through Mahiru connection with Saitō at the Hyakuya Sect.

When Guren betrays Yu again, he does not believe it. He continues to tell Mika that Guren is not dangerous, but still decides to leave Guren and run away. When Guren attacks him, he thinks the Guren's demon is to blame. Yu sees Guren killing Miku in front of him.

They are later reunited again and despite what happened before, Yu still believes in Guren because he said he would save Mika and turn him into a cursed gear. Despite Kimizuki words, he thinks transforming into a cursed gear will save Mika, so he believes in Guren. When Guren asks for their help, Yuu is the first to happily agree. He sees Guren drawing a ritual circle and wants to help him. When Yu finds out that Mika is in danger, he scream at Guren to hurry up. He is happy when Guren says that they will save Mika even if it is a mistake and does not mind that Guren is stepping on him. He does not believe Guren's words that Mika has forgotten him, but agrees with his words that he is Mika's only family and promises not to die. During the battle with demon, Yu often recalls Guren's advice and words to properly subdue Mika and save him.

Sayuri Hanayori
One of Guren's Squad members, Yu is taught by her in class.

Shigure Yukimi
One of Guren's Squad members.

Norito Goshi
One of Guren's Squad members.

Mito Jūjō
One of Guren's Squad members.

Shinya Hīragi
One of Guren's squad members. He is made to battle him when Kureto suspects a traitor amongst them. He assists them in killing Lucal Wesker. Later on, he helps them escape Nagoya.

Makoto Narumi
When Yu first meets Narumi, it is not on good terms. After the Shinoa squad got in trouble, Guren assigned the Narumi squad to work with the newbies. Yu does not like the idea of someone who is older than him bossing his squad around. They are very argumentive at first, but they eventually grow on each other and see each other as someone to protect.

Shūsaku Iwasaki
One of Makoto Narumi's squad members who died against the humans in Nagoya.

Rika Inoue
One of Makoto Narumi's squad members who died against the humans in Nagoya.

Tarō Kagiyama
One of Makoto Narumi's squad members who died against the vampires in Nagoya.

Yayoi Endō
One of Makoto Narumi's squad members who died against the vampires in Nagoya.

Kureto Hīragi
The acting leader of the army and one of those involved with killing everyone in Nagoya. After learning he is the 2nd Trumpet, the "King of Salt", he orders his soldiers to capture him. Yu offered his memories for Kureto and those under him for study to save Shinoa when she was being possessed by the first.

Aoi Sangū
Kureto Hīragi's aide. She is involved with killing everyone in Nagoya. He gives an impassioned defence of Mitsuba to her elder sister when they meet again.

Ferid Bathory
On their first meeting, Ferid asks for Yu, along with Mika to give him blood, but only Mika gives in. They meet for the second time when Yu and his family attempt to escape, and Ferid waits for them at the exit. Ferid slaughters their family in front of them. Although Yu managed to shoot Ferid in the head thanks to Mika's sacrifice, the injury is minor for a vampire. He believed Ferid was the one who turned Mika into a vampire. He has the gun Mika stole from Ferid prior to their escape attempt. Ferid is easily the vampire he resents the most for his massacre of his family-like friends, as shown by how he is the only vampire Yu remembers and when they meet, he gets agitated and ferociously attacks him.

Chess Belle
One of Crowley Eusford's aides who he battles in Nagoya.

Crowley Eusford
Upon the team's arrival to the gates of Shinjuku, Yu instantly recognizes Crowley as a vampire noble. The squad namely Yu manages to inflict some damage on Crowley, earning his interest. Yu is angered by their difference in power despite having a Black Demon weapon. Onwards at Nagoya's City Hall, when he learns that the vampire inside is Crowley, Yu fully agrees with Guren on the noble's strength.

When Crowley surprises Shinoa Squad in the town near the sea, Yu sees they cannot win in a fight so they surrender to him. Yu resorts to Crowley as the means to rescue Ferid and Krul whose information and help they need. He is surprised to hear that Crowley too was once human and heads into Ferid's manor with him before Yu attacks Crowley with a sword in a test of power. He is laid-back and pities the children for getting involved in Ferid's schemes.

"That's enough, Crowley Eusford! We aren't going to fight you!"

- From being wary before Yu now ceases to fight

Horn Skuld
One of Crowley Eusford's aides who Yu would fight on more than one occasion.

Krul Tepes
They had known each other several thousand years ago, when Yuu was still under Shikama tutelage. She treated him warmly, and Yuu listened to her.

Yu didn't meet Krul Tepes in real time, however Mika explains him that Krul is the one who saved his life and she can be trusted, Yu shows sympathy about Krul since she gave Mika a second chance on living. She later discovers that her brother, Ashera, is in Yu's cursed gear after sensing him. When he meets her for the first time, he tells her to shut up since she wanted to get away from Mika. He does not believe her words that Mika will harm them. As soon as Krul says that they can save Mika, he begins to obey her. He also learns that she is Asuramaru's sister and together they escape from Shibuya.

Yu convinces the entire Shinoa squad that Krul can be trusted. He is concerned that Krul has abruptly disappeared, as she promised to help him save Mika. He calls Krul a friend because she was the one who saved Mika in Sanguinem and also because she is Asuramaru's sister. He kneels in front of her when she says that he is not being serious and begs Krul to help him save Mika and she agrees. He listens to her, telling that she knew Mahiru and about their deal.

Lucal Wesker
The first noble vampire Shinoa Squad kills. They work in tandem with Narumi Squad and Shinya Hīragi where Yu leads the attack against the fifteenth progenitor.

Asuramaru
Asuramaru is a former vampire, who became a demon, and was cursed into a sword. He was Mahiru Hīragi's former weapon, and following her death, he becomes Yu's cursed gear after he makes a contract with him. Until Yu weakens the curse binding, Asuramaru promises to become his friend. Asuramaru gives him nightmares every night. He waits for an opportunity to take over Yu's body. After the battle in Nagoya, Yu is chained to a wall, and appears with fangs and horns with the wish of getting free. Asuramaru seems to have complete control over Yu's body.

When Yu tries to talk about Asuramaru memories he notes that every time his angel is out of control and his body and heart gets destroyed, he starts regaining little by little his memories, he says he has a feeling that he have a sister whom he regrets abandoning and falls asleep from the headache by remembering. After the Hyakuya Sect captures Yu, in his mind he's has been struck by two long spears weapons, while Asuramaru in front of him he suddenly finds it odd for his memories to be returning.

During the Dark Ages of Greece, when Ashera was a human, Sika Madu brought a slave named Yu to free the imprisoned Ashera. He tried to befriend Ashera, such as promoting him playing with him. However, Ashera was not interested but promised him that he will play with him someday if he got used to his situation. Ashera was not aware that Yu possessed seraph powers at that time, as the latter was astonished when he saw angel wings appear behind his back.

In the present day, Yu allows Asuramaru to take possession of his body in order to escape Guren. When Yu sees Mika wounded, he pleads with Asuramaru to save Mika. Thanks to Asuramaru's words about Mika, he finds the strength to move on and not resign himself to death.

When Yu finds out that Asuramaru is a traitor, he is shocked and does not want to believe it. He goes to the world of Asuramaru to talk to him. He says that he does not care what goals he has, but if it means that he will hurt Mika, then he will hate him. When he hears Mika's voice, he becomes even more convinced of this. He asks Asuramaru if he is really doing this and hurts his Mika. He says that he will kill Asuramaru and exclude him from the family if he does not stop and is seriously angry with him. He wounds Asuramaru and exits his body, surprising Asuramaru and the rest of the demons. He is surprised when he learns that Asuramaru is Shikama's ally.

"Hey!! What's wrong with you?! I thought you were my family!!"

- Confronting Asuramaru who was troubling Mikaela

When Yūichirō realizes that Asuramaru is indeed on Shikama's side and harms Mika, he concludes he is an enemy. Not considering his questions Yu forcibly changes Asuramaru into his weapon form.

Shikama Dōji
Shikama Dōji seems to be familiar with Yu, as after seeing him in Asuramaru's mind Shikama Dōji tells him its been a long time since he last saw him. Prior to becoming the demon Shikama Dōji, Sika Madu buys a slave named Yu with him to free the imprisoned Ashera and later tries to befriend Ashera, he used to obey every Sika Madu orders, having been with him for a long time likewise Sika Madu is fond of Yu and shows interest in him for unknown reasons. It is later revealed that Sika Madu only uses Yu such as the case when he used Yu's blood to turn Ashera into a vampire. He has no qualms of discarding him if he deems useless but Sika Madu kept Yu due to his blood compatible with Ashera which he takes interest in.

Later on Shikama Dōji invades Asuramaru's heart and Yu comes to the rescue. Seeing both Asuramaru and Yu are in good terms he is delighted he also tempts Yu about his past as he known him for a very long time despite Yu's denial. He defeats Shikama Dōji seemingly. telling Yu that he was just supposed to be another empty vessel. Yu wonders who he is as he knew his past.

Yu later sees Shikama take possession of Shinoa's body again and is surprised. He hears him saying that Mika is his child and he is saving him, so he is their ally.

At some point in Ancient Greece, Yu learned that had been created by Shikama to resurrect Mika. With him trying to capture demon Mika, Yu sees Sika Madu as a foe to try and defeat.

Noya Hienma
Back in the Dark Ages of Greece, Noya seemed to know quite a lot about him. Though appeared cautious as the young Yu approaches the corpse of "Mikaela", taking interest in it, Noya tells him he could call it a fun toy. Noya helped young Yu see what is in the coffin before killing him. Noya did this believing it would save him, Ashera, and Krul and it's not a problem as Sika Madu will create more Yu's anyway. When Yu goes back to Mikaela's corpse, Noya follows him. They discuss the possibility of Mikaela being able to wake up if Yu calls him many times, to which Noya replies that he is not. At some point, Yu greatly annoys Noya with his shouts and he kills him. When a new Yu is born a moment later, it starts to make noise again and Noya again kills him.

In the present, upon seeing a fully grown Yu, Noya is surprised.

Gekkouin
The demon who made a contract with Yoichi. They first meet when Gekkouin takes over Yoichi body. He says that Yoichi will never kill him because they are friends, while Gekkouin says he is naive. When Gekkouin tries to take possession of Yoichi body again, he is worried. He learns that he is an ally of Shikama and is angry with him for harming Mika. They meet for the first time on his real form in Mika world. Later, Yūichirō attacks him by cutting his arm off then avoiding his Thousand Arrows of Light and One Thread, One Glint powers. Yu recognizes Gekkouin from Kiseki-o mentioning his name. After telling Gekkouin that he is too slow Yu cuts him apart at the neck and waist.

Kiseki-o
The demon who made a contract with Kimizuki. When Kimizuki first activates Kiseki-o's ability, the Devil's Coffin, he is afraid of it. During the battle with Crowley, Yu is swallowed by Kiseki-o who wants to eat him. He is surprised when Kimizuki receives more power from Kiseki-o and is happy. When Yu enters Asuramaru's world, he sees Kiseki-o's coffins and concludes that he is also Shikama's ally. They first meet face to face in Mika's world where Yu attacks Kiseki-o for his actions against Mika. Familiar with his coffins Yu tells the demon he is going nowhere before dismembering Kiseki-o.

Demon Mika
Seeing the Mika reborn as a black demon he means to rescue him. Fighting off Asuramaru with Gekkouin and Kiseki-o for that purpose Yu speaks to demon Mika and with no response says he will save him. Yu places his hand into demon Mika's chest as he does so. After pursuing Mikaela in the store in Nagoya where he found Mika again Yu was surprised to learn that he was not recognized. Even though he was told Mika would have no memories as a demon Yu feels that Mikaela chose this store location and so knows who he is. When Mikaela spoke as a demon meaning to devour his desires and possess him Yu was more than happy to allow that to happen and interacts with the demon.

"What, you're hungry? Okay! I totally don't mind if you nom on me."

- Happy to have Mika eat his desires.

After recollecting Guren's words on whether Mika would want to go on if it involved Yu perishing he reversed this position.

"Yeah, if I left you beat me, you'd wind up crying after. So I guess I can't let you win. I promised everyone I'd come back alive too."

- After recollecting Guren's words Yu changes from being fine with Mika consuming him to opposing it for Mika and his squad's sake.

With demon Mika attacking, Yu is more than capable of fending off his assault and responding in kind. Acting as if in a friendly sparring match Yu asks whether he is ready before directing an attack above demon Mika which breaks through the ceiling. Yu joins demon Mika in the air and asks if he is ready. While Yu's memories are being accessed, Yu uses the moment to stab demon Mika and see that they have the same deepest trauma which involves the loss of their family. Yu mentions their family where the desire to protect them can be for demon Mika to devour as he tries to have him become his demon.

Mikaela
"Mika'll wake up for me! Cuz it's my job to wake him up! I was born to do it. Father told me so! So if i just call his name enough, he'll wake up! Right, Mika? You'll wake up for me, right? C'mon Mika! It's time to get up!"

- Yu tries to convince Noya that he can wake up Mikaela and tries to wake up Mikaela's corpse.

Yu as a child in the past knew Mikaela since ancient times. Yu saw him in his coffin for the first time and immediately showed interest in him. Yu called him "a pretty girl," but was quickly killed by Noya. Later, Yu learned that he was created in order to resurrect Mikaela. After that, he began to often go to Mikaela's coffin and tried to wake him up. Yu said many times that this is his goal, because he was born for this and if he calls Mikaela, he will wake up for him. Even when Noya told him it was impossible, Yu continued to call for Mikaela and tried to wake him up.

Mirai Kimizuki
Shihō Kimizuki's sister and an awakened Seraph of the End. He fights her in his seraph form and wins. He later resolves to help rescue her.

Sixth Trumpet
An angel whom Yu fights and wishes to save him despite the Sixth Trumpet have no desire to listen to him. Yu keeps fighting him together with Asuramaru whom he discovers he also has a demon inside. Eventually, Yu and Kimizuki were able to stop him by pinning him down and injecting him with a drug and now appears as a human. This also this puts an end to the Horsemen of the Apocalypse.