Yoichi Saotome

Yoichi Saotome (早乙女 与一) is one of the main male deuteragonists of the Seraph of the End: Vampire Reign manga series. He is a member of the Japanese Imperial Demon Army as well as Shinoa Hīragi's squad in the Moon Demon Company.

Appearance
Yoichi is an average-height boy with medium length, brown hair and large, dark green eyes. In the manga, his hair appears spiky, less bouncy and thinner than his anime appearance.

At the beginning of the series, he is shown wearing his school uniform: a gray with light blue design gakuran.

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. He usually wears the cap and cape as well.

Personality
Yoichi has an equilibrium of kindness and altruism, giving him an optimistic and sweet personality. This gives him a strong mental balance against his demon, who takes the form of his sister. He lacked passion to kill vampires and fight and avenge his sister originally, but as he got to know his new "family", he began to see the reason that he was there. Yoichi does dislike conflict amongst friends, but conflict on the battle field doesn't bother him anymore. As time passed, Yoichi is shown to be much more confident with his skills, sniping down three Horsemen at ease by himself.

Yoichi is usually the peace maker around Shinoa's Squad. Yuichiro and Kimizuki are usually fighting, and Yoichi often ends up in the middle of it. He has developed a love for his "family" that impacted his personality greatly. He used to get very nervous and stutter a lot, but the closer he got to the Squad, the more confident he got. He doesn't question his self-worth as much as before, and instead focuses more on protecting his new "family".

However recently, while speaking to his demon Gekkōin it is revealed that Yoichi actually has a darker, twisted side to his personality. He never shows this side to his friends, keeping it only to himself and his demon. He tells Gekkouin about his desire to make Lacus suffer before killing him, as a retribution to Lacus killing his older sister, Tomoe. Due to the fact that Yoichi doesn't want his friends to become wary of his true desires, he hides it away and never reveals it to anyone.

History


After the apocalypse began, Yoichi and his sister were in their home when vampires arrive. Tomoe pushed him under the bed and told him not to come out for any reason. Then Lacus Welt opened the door, grabbed his sister, and fed on her until he dropped her corpse on the ground. Yoichi watched from underneath his bed, unable to do anything. Another vampire, René Simm then informed Lacus that they were being called to HQ, so they left.

Like his sister, he was one of the children that was being experimented on by the Hyakuya Sect 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 eight years ago.

Second Shibuya High School Arc
Yoichi wanted to become part of the Moon Demon Squad of the JIDA, claiming his intention is to avenge his sister. He asked help from some students (Satoshi Yamanaka, Yūji, and another student), who claimed one was accepted as a member of the Moon Demon Company. Since he failed the test the first time, he wanted to be able to retest on getting in. They bullied him and made him run errands in order to receive their help, but the students lied about the Moon Demon Company. He is the first student to get close to Yu, and Yu tries to fight the bullies until Shinoa informs him that harming a civilian will lengthen his sentence. When a vampire breaks loose from a nearby laboratory, Yu attacks it. As the vampire is about to drink from a student she captured, Yoichi tackles her, saving the girl.

When Yu is outside later, Yoichi tackles him with a hug, accidentally making him pass out after hugging him so ferociously with a dislocated shoulder. When Yu wake up, Yoichi is at his side with Shinoa. Since Yoichi counts as Yu's first friend, they are both enlisted in a vampire extermination unit and join the Moon Demon Company.

Later on, those same bullies chase down Yoichi, asking him to make them his disciples. They ask him to save Yūji, who entered a class-1 restriction zone and became possessed by a demon. Yu grabs onto the axe Cursed Gear, and Yoichi is there with Shinoa when he comes to.

He attends his first class for training as part of the Moon Demon Company with Yu, and Guren introduces him as "the crybaby." During their first assignment in pairs, Shinoa jumps to be Yoichi's partner, forcing Yu and Kimizuki to pair up. When Shinoa reports candidates for the Black Demon Series, she says both Yū and Kimizuki have strong desires and heartbreaking kindness; she does not list Yoichi, who she believes does not have strong enough desires.

Yu earns a zero on their first Japanese spellcraft exam. While Shinoa responds by passing it around and Kimizuki shows off his perfect scores for spellcraft in three different languages, Yoichi sympathizes with Yu, bringing up the fact that Yu was held in a vampire city when he was little. Yoichi suggests that English and Latin may be easier for him, and Yu tries to explain until Kimizuki interrupts him; later on, Yu hints that he did not receive any schooling at all as one of the livestock. Yoichi tries to make peace when Yu and Kimizuki start fighting again, but only the appearance of Guren distracts them enough.

In her report, Second Lieutenant Sayuri Hanayori, their teacher, states that Yoichi is the most stable of his entire class. When Guren tests them all, Yoichi does not even feel the attack and asks what is wrong with everyone. Along with Yu and Kimizuki, Yoichi tests for Black Demon Series Gear. Sayuri expresses concern that Yoichi's heart is not strong enough to accept the demon. Guren simply says that Yoichi will die if he fails and asks Yoichi if he still wants to continue. Kimizuki and Yu tell advise him to leave. He continues anyway and contacts his demon. Unfortunately, the demon takes the form of his dead sister, taking him off guard, and the demon, Gekkouin, possess him, turning Yoichi into a man-eating demon. The demon feeds him flashback after flashback of his elder sister's death at the hands of the vampire Lacus Welt. His demon claims he has no strong desire for revenge.

The possessed Yoichi attempts to kill Guren, Shinoa, Yu, and Kimizuki. Guren orders Yu and Kimizuki to kill him as their first assignment. After some fighting, Yu throws down his sword, telling the possessed Yoichi that he cannot kill him. He tells Yoichi to snap out of it, but it does not work. Guren yells at Yoichi, asking him if he is going to hide underneath his bed and watch his family die again. This pulls Yoichi to his senses, and he breaks free.

He fiercely hugs Yu again, crying as Yu pats his head. Guren gives them their next orders, and Shinoa wonders if he planned this from the start.

Shinjuku Arc
Mitsuba Sangū joins their squad as the fifth member, and Shinoa is in command. He enters the ruined city for the first time. When Yū walks into an obvious vampire trap to save a child, Yoichi supports him against a Four Horsemen of John by firing arrows. During the skirmish in the Omotesando Station, Yoichi also fights against the vampires.

On their way to Shinjuku, they crash into Thirteenth Progenitor Crowley Eusford. Yoichi is the first to attack, but Crowley activates his sword and easily blocks Yoichi's attack. Shinoa and Mitsuba defend Yoichi when Crowley counterattacks. Fortunately, Ferid calls Crowley away. As the squad proceeds, Shinoa coaches them on drugging up.

When Yu freezes on the battlefield against Mika, Yoichi is the first one to notice and ask if something is wrong. When the vampires attack, a vampire easily pins him down and bites him, drinking his blood. Reinforcements save him and his squad.

Post-Shinjuku Arc
When Yu wakes up from his coma, Yoichi is there sleeping at the end of the bed. When Yu wakes him, Yoichi is overjoyed to see him, embracing Yu again. He informs Yu that Yu was the only one badly injured before he informs the rest of the squad. When Lieutenant General Kureto Hīragi questions Yu, he uses Kimizuki and Yoichi as hostages, having them stabbed in the shoulder every time Yu hesitates. Afterward, Yu supports Yoichi when they leave. In private, Yoichi and Kimizuki discuss what happened.

Yoichi arrives with Mitsuba and Kimizuki for their meeting with the rest of their squad plus Guren. Their training actually begins in the ruined city of Shinjuku, but Yoichi can already manifest his demon, which should be impossible. Yoichi easily takes out three Horsemen from a distance. He said manifestation just occurred naturally for him while talking to his demon in his sleep. He says they talked about their favorite colors yesterday. Yu and Kimizuki both try and fail to do the same.

Shinoa and Mitsuba explain the types of demons and the next step of training, which is unnecessary for Yoichi. Yu goes first, and while he is unconscious, the squad agrees to tell Yu everything that happened during the battle. During the night, Shinoa and Mitsua tease Yu and Kimizuki as a yaoi couple, which Kimizuki denies. Yoichi tells Kimizuki that they are right about him being so nice, but the girls quickly warn Yoichi to not fall for Kimizuki's Nice Guy act and say that it will get him in trouble. Yu begins reacting to his demon after twenty hours go by, and he finally wakes up after succeeding in making Asuramaru yield. Kimizuki goes next, attacking Yu voluntarily when he wakes up. Shinoa reveals that the detailed reports on the past of all three boys have been removed from the army's intelligence department.

They meet at Shinoa's apartment at a later date. The group decides to remain loyal to Guren.

Nagoya Arc
On their way to the Ebina Rest Stop, Yoichi volunteers to take out a Horseman, but Yu insists on doing it instead, resulting in a series of pranks by Shinoa and Mitsuba. They claim that this was all Yoichi's idea that caused them to arrive late, and Yu takes the blame. The three boys meet Sergeant Makoto Narumi and his squad as the two squads are paired together for this mission.

When he hears Yu screaming during his punishment, Kimizuki follows the others inside. Guren challenges the squad to a test: Guren, Mito Jūjō, and Shinya Hīragi in a fight against her entire squad. He gives them ten seconds to prepare. Shinoa explains that her ability is to detect anything within the attack radius of her scythe before she assigns Yoichi to keep Shinya at bay and orders the squad to stay within the radius of her scythe.

Shinya fires Byakkomaru, surprising Yoichi when the materialized tiger appears at them from behind. Guren slips past Yu and breaches their lines. He tells Shinoa's squad that it is over as all their friends are dead. Guren scolds Yoichi and Kimizuki for being too slow. He could have killed Shinoa with his first strike, and Mitsuba was already incapacitated. Since they lost their commander, the squad was already done for.

He introduces them to the other soldiers as 16-year-old rookies and states that three of them bear black demon weapons. The combatants evaluate their performance. When Shinya used his special technique to shoot from behind, he turned Kimizuki and Yoichi's attention to their backs. Shinoa's squad agrees that they desperately need to work on their teamwork, and the operation commences. The squads mobilize and head to Nagoya. When they commence their operation at Nagoya, Shinya coaches Yoichi on sniping. Yoichi is very nervous, but Shinya manages to calm him down and make him relax. He informs Yoichi that their duty is to stay calmer than anyone to kill their enemies and back up their allies. In the case of a retreat, a sniper must also kill any allies who fail to escape before they can be captured and tortured. This surprises Yoichi, but Shinya tells him that is only as a last resort. They fire at Fifteenth Progenitor Lucal Wesker, who sacrifices his aide Esther as meat shield. He swings at Yoichi and Shinya, making them run and hold on to their perch for dear life. When Kimizuki goads Lucal into attacking, Yoichi and Shinya support the attack by firing from the back of the group. While everyone congratulates each other, Yu blows off Kimizuki and goes to complement Yoichi, smacking him on the shoulder.

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.

Once at Nagoya City Hall, Shinya and Yoichi prepare to snipe Crowley Eusford. As soon as Yoichi fires Gekkōin at him, Crowley catches it's manifestation and flings it aside. Yoichi recognizes Crowley as the vampire noble his squad rammed a jeep into on their way from Harajuku to Shinjuku during the previous vampire attack.

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 his 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.

Shinoa Squad fights to rescue Guren Ichinose, and Guren's squad soon joins them. They rescue Shinya Hiragi and are forced to escape, leaving Guren behind.

After his flashback, 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. Yoichi along with Mitsuba is shocked by this.

After Yu rushes off to fight Crowley, Kimizuki captures Yu with his demon and knocks him unconscious. The squad runs toward Shinya, who orders them to move. Vampire reinforcements are coming. They join with Narumi Squad and many injured soldiers. They flee, and Rika Inoue reports seeing a single vampire straight ahead. Shinya says they can handle one noble and orders them to keep pushing forward. The vampire attacks the Moon Demon Company without killing anyone, but Yoichi recognizes him as Yuichiro's family. Shinoa calls out to Mika which he demands she return Yu to him. Kimizuki says they have to stop Mika before he kills them which Yoichi protests. Mika reaches for Yu which leads to Mitsuba trying to block him, but he smacks her axe away. Kimizuki drops Yu while trying to block Mika and says he cannot have Yu, but Mika throws him aside. Yoichi then jumps onto Mika's back as the latter begins to lift Yu from the ground. 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 as Mika is their family so long as he is Yūichiro's family. Mika knocks him off as well, telling him to not be stupid and to die.

Shinya uses the distraction to stab Mika through his back and chest. He tells Yoichi that he did excellent work and this battle is over. He tells Mika to die, alarming Mitsuba and Yoichi.

Kimizuki, Mitsuba, and Yoichi join Shinoa, stepping between Mika and the other humans as well. Yoichi says that they've already decided on their motto: "Family takes care of family." The squad then charges at the Moon Demon Company while Mika flees with Yu. Shortly after Mika flees with Yu, vampires rain down around the Moon Demon Company. After seemingly escaping the vampires, Shinoa and her squad, sans Yu, run to Nagoya Airport for their rendezvous. Mitsuba says the attacks against them have stopped, but the vampires are most likely still pursuing them. Kimizuki asks Shinoa if she has more information on their assignment.

Later on, a van pulls up at Nagoya Airport where Aoi Sangu and Kureto Hiragi steps out. Shinya Hiragi and the members of Guren's squad are immediately alarmed, surprising Makoto Narumi with their reaction. Yoichi and Kimizuki recognize Kureto as the one who tortured them while Shinoa and Mitsuba are concerned.

After Kureto orders Aoi to kill the "sacrifices," Shinoa orders her squad to quickly prepare to retreat. As Aoi launches chains from the ground, a pair of chains strike down at Narumi from above, but Mitsuba and Kimizuki block the attack. Kimizuki yells at him to not give up yet. Yoichi fires arrows at Kureto, which Kureto easily deflects. Shinoa and Mitsuba order a retreat, and Shinoa commands them to take their curse stimulant pills. During the fight Yu and Mika come to their aid, and then some time later, the vampires and JIDA soldiers come in and fight each other. Yoichi is saved from a couple of vampires by Shinya, who tells him and the Shinoa squad to run while he and the Guren squad backs them. Yoichi flees with his squad while fighting through the enemies.

During the Mirai/Abaddon crisis, as Yu loses control of his Seraph, Yoichi is able to confirm the spiraling column of flames to be Yu going berserk once more. Awakening in his seraph mode, Yu defeats the demon Abaddon and later stabs himself through the chest with his cursed gear.

As the squad makes their escaped from Nagoya Airport, Shinoa tells her squad that they are now seceding from the Japanese Imperial Demon Army. Soldiers chase them and order them to hand over Yu, who Yoichi is carrying on his back, but Mika appears and kills them.

Three months later, the group is near the sea.

Post-Nagoya Arc
Horsemen attack the village, so with the exception of Makoto, the group fights four Horsemen. Afterward, the villagers thank 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. Shiho states he will do absolutely anything to save his sister and even betray the rest of them. 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 asks if he owes them a favor because they gave him blood, but Shinoa says no. She says that blood was for helping a friend but says she would love to hear any suggestions if he has them.

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.

While the group is on the beach Mika and Yu begin discussing Ferid Bathory until Yu notices the sound of a car engine. Yoichi rushes to the roof of a nearby building and uses his cursed gear to see Ferid and Crowley driving toward them. Shinoa orders them to take their curse stimulant pills and flee. As they run, Yu and Mika say that Ferid is a seventh progenitor, the second strongest vampire in Japan after the queen herself. Mika and Yu talk about Ferid's mansion and the past, but Shiho tells them to focus on running.

Yoichi chips in and says that the whole world is screwed up, and the only thing they can be sure of is that all of them are friends.Crowley lands in front of them and strikes Mitsuba with his sword, sending her flying. Mitsuba goes flying after Crowley’s blow but is shocked to realize she is uninjured. He throws her to the ground. When Kimizuki asks what they will do, Yoichi responds first by manifesting his bow and saying they must rescue her.

Mitsuba latches onto Crowley’s leg and orders the squad to abandon her and flee since they cannot waste time there. Yoichi refuses and shoots at Crowley, who easily deflects his shots. For the first time, Yoichi summons his demon to the extent curse marks cover his face. He fires again. Kimizuki steps in next. Makoto asks what they are all thinking, and Shinoa orders everyone to assist Kimizuki.

Yu surrenders to Crowey and Ferid until Ferid presents Akane's head in a jar to them, sending Yu's demon out of control and making him attempt to kill Ferid. Mika gets Yu to struggle against the demon temporarily. After Kimizuki calls a truce with Crowley and Ferid, the squad departs on a bus with Ferid and Crowley is driving.

The squad take a bathroom break. In the boys' bathroom, Yu rants about Guren taunting them with information but never giving them answers. The boys tell Yu to quit shouting. Yoichi mentions that Yu has started acting like his old self since he received that medicine. Yoichi says Yu had been acting colder since his demon took over.

The girls then enter the boy's bathroom where they discuss their situation and the Seraph of the End. Going back to the topic at hand, they decide they must betray Ferid before he betrays them. They crouch together and whisper to come up with a signal of when to attack Ferid en masse.

Osaka Arc
The squad eventually gets back on the bus and are driven to Osaka Bay. The group disembark to see an army of foreign vampires. While Mika gets information from other vampires, Yoichi recognizes the two vampires that Mika is talking to and recalls when Lacus killed his sister. Curse marks appear around Yoichi's eye as he says Lacus's name. Curse marks appear over the left side of Yoichi’s face as he struggles against Gekkouin. His pupils become slitted, and horns appear as well. In his mind, he faces Gekkouin, who sits on his sister’s bed and leers over the illusion of her corpse. Gekkouin reminds Yoichi of his sister’s death and asks him why he is not getting angry. Yoichi tells him to stop and to make the illusion go away. Gekkouin refuses, stating that Yoichi will forget about his revenge if he does that. Yoichi says he is not running away and points out that even Gekkouin cannot handle all of the high-ranking vampires.

When Gekkouin says he will get help from Yoichi’s buddies, Yoichi says he refuses to get them mixed up in his revenge. Gekkouin says Yu is using Yoichi for his problems and is taking advantage of them to get his family back, but Yoichi says that is completely different. He explains that Yu is a nice person who refuses to give up and keeps trying to get his family back and to protect his friends. He says that is truly amazing and insists that despair and hopelessness would have devoured him if he had not been lucky enough to become part of his family.

Gekkouin points out that Yoichi is implying he is not nice like Yu, and Yoichi agrees. He says he is so mean and nasty and petty that he cannot let the others find out. He explains to  Gekkouin  that they must make Lacus suffer and cannot kill him quickly or cleanly, but they cannot let his friends know. Gekkōin laughs and agrees to help him.

Yoichi returns to the moment. When Yu asks him what is wrong, he says he is just worn-out and says he might take a nap.

As Ferid and Krul are begin their punishment, Yoichi takes note of the exposure torture and glances at Lacus. Crowley then takes Shinoa squad to Ferid’s fifth personal estate in Osaka, and Yoichi is still holding Akane's head. Yoichi watches Mika and Narumi argue about how the Seraph of the End experiment should not be recreated, and Yoichi tells them to calm down. Tenth Progenitor Fuola Honte comes out of the mansion and attacks them. Yoichi does not fight as he is still holding Akane's head.

Crowley steps out of the mansion, approaching Fuola. Fuola attacks Crowley, but Crowley beheads him, and slices him in half. The group comments on Crowley’s strength. Crowley then spars against the squad and reveals his strength is at the level of a seventh progenitor.

Since they have decided to Ferid and Krul, Crowley then tells them they must get stronger quickly since they had difficulty fighting a tenth and must face a fifth progenitor, Ky Luc, in order to rescue them.

Shinoa squad watches Yu berate Crowley for not telling him he was a former human and they think about how vampires seem like predators. Narumi asks Mika about how much humanity he has left but KImizuki stops him. Yoichi states that species doesn't matter because humans kill other humans so vampires could be trusted if they didn't kill their family. Mika states his humanity is vanishing but his feelings for Yu have not changed. The rest of the squad enters the mansion looking for food and Crowley directs them to the kitchen and says after they eat he will bring them into the cellar. After eating, in response to Crowley's warning and protest by Makoto of him going berserk in the basement that holds the bodies down there, Yu asks Yoichi to give him Akane's head to carry. He accompanies the squad down into the basement and some time later, Guren shows up to everyone's (except Crowley, Mika, and Shinoa's) excitement.

When Guren tells Kimizuki that his sister, Mirai, is alive, Yoichi says to Kimizuki that he is glad for him. With everyone he listens to Guren's explanation of the person that has been manipulating the Hīragi family. Mika then attacks Guren against Yu's protests, which leads to Yoichi and Kimizuki to step in with Yoichi asking if they can talk this out. This causes Mika to reluctantly stop his attack. As Guren explains his plan to revive the people that died from the apocalypse virus eight years ago, Yoichi brings up how his sister died during those years so will not likely be revived since there probably won't be anything left of her body that was buried. With Mitsuba he then watches an argument between Yu and Mika over Yu deciding to go along with Guren's plan.

While Yu works on controlling the seraph with Guren, Crowley, and Mika monitoring; and with Shinoa, Makoto, and Kimizuki are trying to read the spell-books in the library, Yoichi ends up waiting with Mitsuba in the dining room. The two remain seated at the table until they hear a scream, which they recognize as Yu going berserk, and they go outside and watch as Yu recovers. Three days later, Yoichi has Gekkoin aimed at the vampire guarding Ferid and Krul, Fifth Progenitor Ky Luc. He counts down from ten seconds and fires at the same time as Yu launches himself at the vampire.

Shibuya Arc
Yoichi can only observe as Shinoa is being transformed into a vampire. He, along with everyone else is told to get lost by Kureto, and to Yoichi's surprise Yu is then robbed of his freedom and taken away as an experimental subject by Kureto's guards. Joining Yu along with Mitsuba, Narumi and Kimizuki, Yoichi hears what sounds like a battle. He calls Kimizuki as he leaves to check his sister and looking between him and Narumi, Yoichi says he is going with Kimizuki.

Calling to Kimizuki, he has his bow drawn and tells him to come this way as he leads Kimizuki who is carrying his sister away.

There are further explosions occurring in the ruined city of Shibuya, Yoichi appears panicked and asks what is going on in, and whether everybody is dead. Told to forgot it and run, he asks where before mentioning that guy said they should go to Shinjuku. Hearing that Kimizuki means to leave Tokyo and save his sister, Yoichi says he will help him.

Appearing relieved, he points out that Guren is ahead, yet his expression changes when he sees that the Lt. Colonel has horns. Then bewildered, he asks what Guren just said when he stated he needs to kill Mirai. Yoichi joins Kimizuki in activating his cursed gear as his bow Gekkouin flares up.

Unable to do anything due to the suddenness, Yoichi finds it hard to believe that Guren just stabbed Mirai. Shouting for Gekkouin to please stop him, Yoichi fires his weapon point blank into Kimizuki who in fury was turning into a demon. Looking down to Kimizuki’s sorrowful face, Yoichi’s attention is then drawn to Mirai being dropped. Tearfully, he tells the Lt. Colonel that was a really mean thing to do and why would be do something like that.

Told to collect the body and leave Shibuya, Yoichi questions this then thinks Guren means to say that it is possible to bring Mirai back to life. Asking is it not the case that bringing humans back to life is supposed to be taboo, Yoichi thought that was what caused Guren all this pain. Hearing that his sister’s body is in storage causes Yoichi to stand there quietly horrified. Curse marks appear in his eyes as he asks what Guren just said, and he calmly invokes Gekkouin.

Firing, the shot has a negligible effect on Guren’s hand which blocks it. Instructed to leave Shibuya again, Yoichi tells Guren that not on his life is Yoichi going to let Guren get away from him. Instructing Gekkouin to kill him, Yoichi fires anew.

Whilst carrying Mirai with Kimizuki on his back, he is relieved to find Shinoa and Mitsuba. Answering that the Lt. Colonel killed Mirai, Yoichi also mentions that he can revive her and his sister whose body is in storage. Believing they should not get in his way, Yoichi then mentions that revival was done before eight years ago which caused the catastrophe that destroyed the world.

After standing alert with his bow Yoichi is in the jeep driven by Kimizuki before using his cursed gear to check for Yu. Seeing him fall through the air, Yoichi tells the others that Yu is crying. He fires to clear the obstruction ahead as Kimizuki drives towards Yu and exclaims "yipes!" as they traverse the debris strewn road. With Shinoa's demon used, Yoichi watches open mouthed as Shinoa is pulled out of the vehicle. He grabs Mitsuba's leg before calling for Kimizuki but only manages to seize his glasses. Safe back in the vehicle, Yoichi does not agree with Shinoa's claim that the power of the first vampire is amazing. Yoichi uses his cursed gear aim and says to the others that Yu has noticed them.

Having escaped Demon Army territory to an apartment complex Yoichi carries Krul as he thinks how this is the vampire queen. Laying her on a bed he notes she is sound asleep and looks like a child. Joining Mitsuba and Shinoa he listens to Yu and Kimizuki then comments on whether they are actually going outside. Asking if they got anything from what Yu said he is intrigued on what Shinoa has and is delighted to hear there is actual soda. Whilst Yoichi does not feel they have time for this he does think they cannot rush off to with Guren and the Demon Army the way they are now. He contemplates further that the vampire queen who Yu swears is their friend is out cold and they cannot decide anything about her yet either. Aware that Yu and Kimizuki really did start fighting Yoichi questions whether Shinoa is sure they should not stop them. Perplexed at Shinoa and Mitsuba he asks why they are both so bright red in the face before discovering that the drink they have is alcoholic. Wondering if they are not in a critical emergency right now Yoichi sighs that it is kind of nice to see everyone happy and that maybe he will drink too. He is heaving into a trash can by the time Krul wakes up. Laying near it Yoichi can only point when Kimizuki returns to the room and asks why the floor is covered in barf. Unresponsive to Krul speaking Yoichi is then held up by Kimizuki and answers that he did allow his curse to run rampant to speed up his metabolism to deal with the alcohol before being picked up by him. Yoichi is crouching and thinks he is sobering up and stares intently as Yu implores Krul for her help in saving Mika. With Krul asking how many of them bear black demon weapons Yoichi answers that he does and raises his hand at Krul's request.

Natural abilities
Yoichi has high psychic resistance, but he's mentally very weak. His resistance is so strong that he does not even feel Guren's attack against them when he tests them for the Black Demon Series. He is able to manifest his demon without training, something which Shinoa observed that a normal person isn't able to do. He appears to get along with his demon, more or less, and the bond he eventually forged with his demon over his series of adventures allow him to develop his abilities more.

It is later revealed that there is actually a darker side to Yoichi, admitting that he does truly seek vengeance for his sister's death, and it's that determination that fuels and pleases Gekkōin, allowing him to draw out more of the demon's power.

He is also shown to be very strong, as he was able to carry Kimizuki and Yu, both of which weigh more than him.

Cursed Gear

 * Gekkouin (月光韻): A manifestation-type demon weapon of the Black Demon series. It takes the form of a big, black bow with glowing green eye-like features at the upper and lower curves of the bow. Yoichi's left eye is shielded by a green pentagram symbol that locks and focus on his designated target, so he can readily begin honing in arrows as preparation to be shot at. It can manifest multiple arrows and can see far away. This allows Yoichi to target multiple enemies as well as seeking them out before they can attack. It is a purely long-range Cursed Gear weapon.

Acquired abilities
Learned the role of a sniper from Shinya.

Seraph of the End: Vampire Reign
"Lieutenant Colonel Guren, Sir! I'll do it!! I want more power! I want enough so that I'll never lose anybody important to me again!!!"

- Yoichi to Guren.

"Th-That can't be right! I do want revenge for my sister—""

- Yoichi to Gekkoin

"B-But... But I... I don't want to run away anymore. I-I want... to protect my friends. I need power to keep them safe. I need power... to drive off the bad guys who'd hurt them! Give me power... Demon!!"

- His motives for needing power from Gekkoin.

"Um... I-I'd like it if we didn't have to fight them again."— ''Yoichi to Shinoa's squad after fighting some vampires"

- Chapter 8 "Mitsuba's Squad"

"...I'd like to go home to Shibuya about now.""

- Yoichi to his squad before entering the battle at Shinjuku

"Oh, come on, guys! Yūichirō's always been a nice guy.""

- Yoichi to his squad while the others are teasing Yu.

"Shoot down my enemies, Gekkouin. Let's protect everyone."

- Yoichi before attacking.

"We are... all friends, right...?""

- Yoichi to his squad

"Aha ha ha! But they're right, you know. You're super nice.""

- Yoichi to Kimizuki

"Guys! Guys! Can't we try to get along?""

- Yoichi to Kimizuki and Yu

"If you're gonna kill me, do it! But... If you're Yuichiro's family, then that makes you our family too!"

- Yoichi to Mikaela Hyakuya.

"Yeah! We've already decided on our motto...'Family takes care of family'."

- Yoichi while protecting Mika.

"Oh no. It's Yuichiro! Yuichiro is going berserk again!"

- Yoichi to his squad

"Um... Mikaela? Was our blood okay? Do you think you'll be able to drink it?"

- Yoichi to Mika

"It... It isn't the Demon Army! It's the vampires!! Not only that, it's him! The one we fought in Nagoya!!"

- Yoichi

"Yeah. He's right, Yuichiro! To be honest, the whole world is really messed up right now... and none of us have any clue what the heck is going on. But if there's one thing we can be sure of... it's that no matter how terrible the world gets—all of us... are friends."

- Yoichi to the group.

"We won't!! We don't abandon our comrades!!"

- Yoichi after Mitsuba tells their group to flee and leave her behind.

"Well, um... Ever since Ferid injected Yuichiro with that medicine, he's started acting like his old self again." (To Yu) "It feels like ever since your demon took over, you've been getting colder and colder toward everything..." (To the group) "I guess what I'm saying is our situation isn't as completely bad as everyone thinks it is. Yu needed medicine, right? Now we have that medicine. Not only that, we learned it might be possible to bring people back from the dead. If that's true, isn't that some very good news...?""

- Happy that Yu is better and placing matters into perspective

"That's...! Lacus. That's... Lacus.""

- Yoichi to Yu after recognizing Lacus Welt

"Urf... Crap... S-Stop... Stop now... Gekkouin...!!""

- Yoichi to Gekkouin after recognizing Lacus Welt

"I haven't forgotten my sister. I'll never forget."

- Yoichi to Gekkouin.

"Because Yuichiro is such a nice person! The whole world is empty and broken, but he refuses to give up! He keeps trying his very hardest to get his family back and to protect his friends. That's amazing! Really, really amazing! If I hadn't been lucky enough to become part of his family when I did, I'm sure despair and hopelessness would've swallowed me up and I'd be dead by now."

- Yoichi to Gekkouin.

"Me? Oh, no. I'm not nice at all. I'm so mean and nasty and petty... I can't let the others ever find out."

- Yoichi to Gekkouin.

"Gekkouin... When we finally kill that Lacus vampire, it can't be quick or clean. He has to suffer. I want him to suffer so badly that he regrets ever being born... But I don't want my friends to know. They can't be allowed to see me like that. Will you help me? Gekkouin."

- Yoichi to Gekkouin.

"What does it really matter who's what, anyway? Humans kill other humans. They always have. So how can we say vampires aren't allowed to have friends? If they haven't killed any of our family, I don't see why we can't be nice to each other."

- Yoichi to the main group.

"Hey, guys. It's awful nice and breezy up on the roof. Mikaela says he wants us all to come up too!"

- Yoichi teasing Mika

"If you do something crazy and we both wind up in over our heads, you could die too. And then who will go and save your sister? I've gotta be there to protect you."

- Yoichi to Kimizuki.

"So this is the vampire queen, huh?"

- Carrying Krul Tepes unconscious

"Oh. Yeah, she has a point. Not with Lt. Col. Guren and the Demon Army the way they are now."

- Thinking to himself how he agrees with Shinoa that there is nothing they can rush off and do right now and why

Trivia

 * In the Japanese industry, "Yoichi" is often used for "bow", but Yoichi's name has a different origin, which the writer, Takaya Kagami, says is a secret.
 * Yo 「与」can mean "to provide" or "award", whereas Ichi 「一」 means "one" or "first."
 * Saotome 「早乙女」 means "young maiden."
 * When Yoichi's design was first created, he was depicted with black hair. This was most likely changed due to his resemblance of Yuichiro.
 * In the light novels, it is confirmed he and his sister are also results of the "Seraph of the End" experiments the Hyakuya sect undertook.
 * In the popularity poll, Yoichi earned 9th place at 879 points.
 * According to the Manga 8.5 Fanbook:
 * Interests/Likes: [Interests] How to take revenge / Cola
 * Favorite Food: Napolitan/ Green tea / Black tea
 * What he looks for in the opposite sex: A girl who he can drag into things.