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. Also featured prominently in other Seraph of the End materials, Yoichi would seek to gain power to avenge his sister, Tomoe Saotome who was murdered by a vampire. Coming into contact with Yūichirō Hyakuya with Shinoa Hīragi, he would also become acquainted with Shihō Kimizuki. Having an innate resistance to demon energy, Yoichi would be a candidate selected by Guren Ichinose to acquire a Cursed Gear weapon. While he failed the trial initially, Yoichi would make a contract with the demon Gekkouin where he could wield a cursed gear bow.

Becoming a member of the Japanese Imperial Demon Army, as well as Shinoa Hīragi's squad in the Moon Demon Company, with Mitsuba Sangū joining the team he is in, Yoichi registers the state of the world when liberating humans from a vampire lair. Heading to Shinjuku with the squad, Yoichi would help defend the city from a large scale vampire invasion. A part of the operation targeting vampire nobles in Nagoya, Yoichi would deal with his nerves working with Shinya Hīragi, along with Makoto Narumi's squad and provide aerial coverage. After identifying Mikaela Hyakuya, he helped him escape.

Resolute in defending his friends, Yoichi fired at Kureto Hīragi who was sacrificing his own soldiers, then joins his squad in deserting the army. Having to work with Ferid Bathory and Crowley Eusford, he learns that Guren wanted to resurrect everyone who died during the apocalypse. In Shibuya with Shikama Dōji active, Yoichi would help Kimizuki rescue his sister, Mirai Kimizuki. Livid that Guren retained his sister's body, Yoichi would act to help Yu and Mika over his own demon, yet while wary of Guren's plan he would help carry it out.

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

He is shown wearing his school uniform: a gray with light blue design. Yoichi also wears the standard JIDA uniform which consists of a long-sleeved black coat with light green details including the, which has a brown passing diagonally over his right shoulder, with 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. Yoichi 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
Having an equilibrium of kindness and altruism gives him an optimistic and sweet personality. Yoichi reacts to conflicts among others close to him such as Yu and Kimizuki by trying to mediate and calm the tension. While such traits are not helpful for his demon, it helps Yoichi himself cope when Gekkouin takes the form of his sister. Professing to want to avenge his sister was a driving force in wanting to join the army, and Yoichi was prepared to take measures for a mere chance at that. Even with his capabilities called into question, Yoichi showed a determination in wanting to make a cursed gear contract for this purpose. Where as a child he followed his sister's guidance to stay under the bed, Yoichi, now older and with other's safety at risk, chose to overcome his fear, and instead act to prevent such tragedies from happening again. This desire to help was effective in overcoming his possession by a demon. With time spent around his new "family", Yoichi began to see the reason to why he was there, and does not question his self-worth as much as before. At ease with everyone, Yoichi is willing to act to assist his friends.

While Yoichi dislikes conflict between his friends, it is not the same on the battlefield against threats. Ready to engage, Yoichi is effective at firing initial shots at foes. He is also on standby to provide cover fire to defend others, effectively working with physical fighters who are battling an enemy. Compromised by an attack, or outright captured, Yoichi is not overtly afraid of the danger, rather acknowledges it and endures in what is bravery, which would seem at odds with his somewhat meek demeanour overall. In taking the time to speak with his demon while sleeping, Yoichi develops weapon manifestation. Fitting into a sentry position naturally, Yoichi monitors an area to provide safety for the squad to train. Alert, his confidence in his skills grew to the point where he could snipe and destroy multiple Horsemen by himself. While nervous during a sniping mission with Shinya out of fear they would impair the secretive nature of the ambush, or outright fail, Yoichi followed guidance to calm himself. He wasted no time in launching a devastating bombardment on targets to clear the area for the ground troops. Yoichi also fired at once give the order at a vampire noble, Crowley, that he noticed.

Attentive, Yoichi observes for danger and often listens to others who make decisions where he is ready to support them. Insightful to others, Yoichi asks his demon Gekkouin what his favorite color is as he builds a rapport with him. With Yu failing his exams, where others tease him, Yoichi sympathizes and understands it was due to his upbringing in a vampire city. Even after seeing Mika fight his way through many soldiers, and knock aside others, Yoichi dropped his weapon and appealed to his sense of family. Not just giving blood, Yoichi asks Mika whether it tastes okay. Anticipating a scenario and acting to avoid it, Yoichi knocks Kimizuki who has turned into a demon out by firing at him to stop him attacking Guren where his life would have been in danger.

In response to certain stimuli, connected directly with the circumstances involving his sister, Yoichi is overcome by a relatively quiet, homicidal rage where he sees murder as the solution. In a private conversation with Gekkouin, he shared a darker, more twisted side to his personality. It was one Yoichi is conscious to never show to his friends, keeping it only to himself and his demon, yet he tells Gekkouin about his desire to make Lacus suffer before killing him. Realizing that sunlight exposure torture existed, Yoichi reacted by desiring this for the vampire who killed his sister. What is a sudden set fixation on killing is also applied to Guren, not after he murdered a young girl, Mirai, but when he revealed Tomoe's body had been kept. Seeing him again, Yoichi had his bow drawn. In such cases, Yoichi is prepared to calm himself, but has outright attacked with his cursed gear.

History
After the apocalypse began when he was a child, Yoichi and his sister, Tomoe, were in their home when vampires arrived. Told to get under the bed and not come out for any reason, Yoichi witnessed Lacus Welt enter, grab Tomoe where he fed on her before dropping her corpse on the ground. Powerless to act, Yoichi remained hidden as another vampire, René Simm then informed Lacus that they were being called to HQ before they left.

Like his sister, Yoichi 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 which would devastate the world. Unknown to Yoichi, Guren knew of this beforehand, thanks to intel provided by Mahiru eight years ago. He would also be unaware that Tomoe's body would be acquired and taken into storage, and that details on his past had been erased. At some point Yoichi would enrol in Second Shibuya High School as normality was returned, somewhat, to certain areas.

Second Shibuya High School Arc
Yoichi aims to become part of the Moon Demon Squad, an elite military group under the Japanese Imperial Demon Army. He sought help from some students (Satoshi Yamanaka, Yūji, and Shishido) after he heard one was accepted as a member of the Moon Demon Company. Since Yoichi had failed the test his first time, he wanted to be able to retest for a chance of getting in. While Yoichi is set on this goal, he is being bullied by the group where he is essentially told to run errands such as acquiring snacks in order to receive their help. With his predicament noticed by Yūichirō Hyakuya, who intervened with Shinoa Hīragi's pressing, Yoichi would share his reasons for wanting to join with them. Detailing that it was to avenge his sister, Yoichi was not discouraged from attempting to join.

After an emergency announcement warns that a vampire has broken loose from a nearby laboratory on campus, Yoichi sees Yu head to fight it. As Shinoa acts to contact members of the Moon Demon Company, Yoichi makes his way to the classroom Yu and the vampire is in. As the vampire is about to drink from a student she captured, Yoichi tackles her, saving the girl.

Finding Yu outside after he was thrown out of the window, Yoichi is relieved to the point where he tackles him with a hug, accidentally making him pass out after hugging him so ferociously with a dislocated shoulder. He checks Yu while being observed by Guren Ichinose and members of his squad who have arrived. Waiting in the medical room with Shinoa, he is there when Yu wakes up. Since Yoichi counts as Yu's first friend, they are both enlisted in a vampire extermination unit and join the Moon Demon Company.

At a later point, Yoichi is being chased by the same bullies from before. Finding Yu, he hears the bullies asking him to make them his disciples. Hearing them raise how Yūji has entered a class-1 restriction zone and became possessed by a demon, Yoichi joins Yu and Shinoa in what functions as a training exercise. Entering a chamber filled with cursed gear weapons, after Yu grabs onto an axe Cursed Gear, Yoichi is there with Shinoa when he comes to.

When attending his first class for training as part of the Moon Demon Company with Yu, he is introduced by Guren as "the crybaby." During their first assignment in pairs for an exercise involving training dummies, Yoichi finds Shinoa jumping to be his partner, where he is denied as Yu's. In class, as Yoichi stands near Yu and Kimizuki, he is discussed by Shinoa when she is reporting candidates for the Black Demon Series to Guren. Where Yu and Kimizuki are said to have strong desires and heartbreaking kindness; Yoichi is not listed, who Shinoa believes does not have strong enough desires. At some point Yoichi was seated in front of Kimizuki in a class taught by Guren. With the lesson concerning how spell circles were created, Yoichi appeared startled at Guren chiding Yu for his behaviour.

After an test in which Yu has received 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. Aware of, and 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. Yoichi tries to make peace when Yu and Kimizuki begin fighting again.

In her report, Yoichi is noted by his teacher Second Lieutenant Sayuri Hanayori that he is the most stable of the entire class. When Guren tests all gathered in the room using the energies from Mahiru-no-Yo, as others are heavily affected and outright collapse, Yoichi does not even feel the attack and asks what is wrong with everyone. Along with Yu and Kimizuki, he heads to the chamber to test for Black Demon Series Gear. Present as Sayuri expresses concern that Yoichi's heart is not strong enough to accept the demon, Yoichi hears Guren simply say that he will die should he fail. Asked if he wants to continue, with Kimizuki and Yu advising him to leave, for all their concerns, Yoichi is determined to proceed.

Participating in the contract ceremony, Yoichi sees his sister killed, and then her eyes open. After they speak, it is only after a while that Yoichi catches on that this is the demon who has taken the form of his dead sister. Caught off guard there, Yoichi hears the demon mention that he does not actually have any strong desire for revenge. His words to the contrary fail to sway the demon, and he is possessed. Yoichi literally becomes a man-eating demon with its own mind.

The possessed Yoichi attempts to kill Guren, along with Shinoa, and Yu, also Kimizuki below. His body is used to hold the large cursed gear bow and fire ranged projectiles. After some fighting where he has been ordered to be killed by Guren, his mind cannot react to Yu throwing down his sword where he appeals to him to snap out of it. It is Guren's shouting on whether he is going to hide underneath his bed and watch his family die again that rouses Yoichi. Pulled to his senses, in the visualization involving being told to hide under the bed by his sister, Yoichi is himself and decides to leave so as to help others, and he breaks free. Fiercely hugging Yu again after the incident, Yoichi cries as his head is patted. Hearing that they are a family now, Yoichi is given his orders.

Shinjuku Arc
Outside the walls of the city, Yoichi is waiting with Kimizuki before Yu and Shinoa arrive. He hears from Guren that Mitsuba Sangū who is also there, is to join their squad as the fifth member, and Shinoa is in command. Formally a part of Shinoa squad, and on their way to a mission to investigate a vampire lair, Yoichi makes his way through the ruined city for the first time. With a girl found being chased by a Horsemen of the Apocalypse, after Yu walks into an obvious vampire trap to save her, Yoichi supports him with his ranged attacks. After making his way underground in the Omotesando Station, Yoichi also fights against the vampires lying in wait where he helps ensure the squad prevails through this entrapment.

Heading on their way to Shinjuku as a next part of the mission, Yoichi finds the city under sttack and comes into contact with a vampire noble. After vacating the truck they are in for it to crash into Thirteenth Progenitor Crowley Eusford, ready to attack, Yoichi is the first to fire, yet finds his projectiles are easily blocked once Crowley activates his sword. Defended from counter fire by Shinoa and Mitsuba, he finds two additional vampire nobles Horn Skuld and Chess Belle arrive. Spared further conflict only because the nobles answer Ferid Bathory's summons to the front lines, Yoichi hears from Shinoa how Cursed Gear Stimulants can help with their weapon capabilities.

Making it to the front lines where Guren is located, when Yu freezes on the battlefield against Mikaela Hyakuya, he is the first one to notice and ask if something is wrong. Due to the vampires on the opposing side of the battlefield, a retreat is ordered yet Yoichi is pinned down easily and he is bitten. Yoichi, along with his squad, and the city, are saved once reinforcements led by Shinya Hīragi and Lieutenant General Kureto Hīragi.

Post-Shinjuku Arc
When Yu wakes up from his coma, Yoichi is there sleeping at the end of the bed. Woken up by him, Yoichi is overjoyed to see Yu and embraces him again. Informing Yu that he was the only one badly injured and that everyone else is fine, Yoichi heads to tell the rest of the squad.

Having already been interrogated, when Kureto with Aoi Sangū questions Yu, along with Kimizuki he is brought in as a hostage. Yoichi is stabbed in the shoulder by a guard every time Yu hesitates and even if he answers questions truthfully. Afterward, Yoichi is supported by Yu 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 which includes Guren. Their curse gear training actually begins in the ruined city of Shinjuku, but Yoichi can already manifest his demon, which should be impossible according to others. Standing guard, Yoichi easily takes out three Horsemen from a distance that he has spotted approaching. Sharing that manifestation just occurred naturally for him, Yoichi adds that he has been talking to his demon in his sleep, they talked about their favorite colors yesterday.

With Yu's training being undertaken first, as he is physically unconscious in the process of talking to his demon, Yoichi hears the others agree to tell Yu everything that happened during the battle, namely how he became a one winged monstrous being. During the night, Yoichi witnesses Shinoa and Mitsuba tease Yu and Kimizuki being couple who care deeply about one another. With this denied, Yoichi tells Kimizuki that they are right about him being so nice, but he is quickly warned by the girls to not fall for Kimizuki's nice guy act or it will get him in trouble.

When Yu begins reacting to his demon after twenty hours go by, and he finally wakes up after succeeding in making Asuramaru yield, Yoichi is ready to help with Kimizuki's training next. While seeing Kimizuki attacking Yu voluntarily when he wakes up, where they test their newfound power, Yoichi is unaware that the detailed reports on the past concerning all three boys have been removed from the army's intelligence department according to what Shinoa has learned.

Meeting at Shinoa's apartment at a later date, Yoichi attends the group meeting to discuss whether Guren is using them. The group decides to remain loyal to Guren.

Nagoya Arc
On their way to the Ebina Rest Stop in a campaign targeting vampire nobles in Nagoya, Yoichi volunteers to take out a Horseman in the road ahead. With Yu insisting on doing it instead, which results in a series of pranks by Shinoa and Mitsuba, while a bystander to the merriment, Yoichi is held responsible as they claim that this was all his idea that caused them to arrive late. With squads gathering at the rest stop, Yoichi meets Sergeant Makoto Narumi and his squad and learns the two squads are paired together for this mission.

Hearing Yu shouting during his punishment after he accepted the blame for being late, Yoichi follows the others inside. The squad is challenged to a test where the five of them will fight against Guren along with Mito Jūjō, and Shinya Hīragi. Given ten seconds to prepare, Yoichi joins his team in gaining some distance between them. Directed to stay within the radius of her scythe that can detect anything, Yoichi is assigned by Shinoa to keep Shinya at bay.

After Shinya fires his Byakkomaru rifle, Yoichi is surprised when the materialized tiger manifestation appears at him from behind. Unable to act as Guren elsewhere slips past Yu and breaches their lines, Yoichi and the squad are declared defeated. Scolded by Guren for being too slow when he attacks alongside Kimizuki, it is detailed how Shinoa could have been killed with his first strike, and Mitsuba was already incapacitated. Since they lost their commander, the squad was already done for.

Introduced to the other soldiers as 16-year-old rookies, Yoichi is one of the three mentioned by Guren that bear black demon weapons. Yoichi's combative performance is evaluated as Shinya explains how he used his special technique to shoot from behind, so 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. Yoichi along with the collective squads mobilize and head to Nagoya.

Within Nagoya where the large scale vampire noble extermination is set to begin, Yoichi is with Shinya located on a radio tower. Very nervous, Yoichi is coached by Shinya on sniping where he is able to calm down and relax. Yoichi hears that their duty is to stay calmer than anyone to kill their enemies and back up their allies. In the case of a retreat, he is also informed that a sniper must also kill any allies who fail to escape before they can be captured and tortured. Although surprised at this, Yoichi is told that is only as a last resort.

Noting his appearance, with the time ready, Yoichi joins Shinya in firing at Fifteenth Progenitor Lucal Wesker, where their joint assaults wipe out his aide Esther Lee who was sacrificed as a meat shield. When Lucal swings his sword to launch a ranged attack at their location, Yoichi runs to hold onto something as the construction begins to topple.

Having made it onto the ground, Yoichi with Shinya near Shinoa and Narumi's combined squads who are attempting to prevent Lucal from escaping and joining with other nobles. When Kimizuki goads Lucal into attacking, Yoichi and Shinya support the attack by firing from the back of the group. With the vampires, including Lucal as a noble are defeated, Yoichi is complemented by Yu as everyone congratulates each other.

On the streets of Nagoya, Shinoa Squad and Narumi Squad wait for the survivors to regroup. Finding Sergeant Aiko Aihara arrive with a bruised, battered, and bleeding face, it is registered the squad only has seven survivors, so eight of them died. Yoichi and his squad take watch while Aihara's rests. After Guren and his squad come above ground, Yoichi as a part of Shinoa squad are reported to have done very well by Narumi.

With a sizeable force having been defeated with members captured, Yoichi's team and Narumi's are ordered by Guren to join his squad and hunt down the vampires behind this act. They are to stage an attack on Crowley who is accompanied by Chess and Horn that will last ten minutes. If they cannot kill him during that time, they will retreat and tackle the next mission with the numbers of soldiers that they have.

Overlooking Nagoya City Hall, Yoichi's ranged capabilities are made use of as he joins Shinya in preparing to snipe Crowley. Locating him, as soon as Yoichi fires Gekkouin at him, his manifested projectile is caught by the vampire noble where it is flung 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 and alerts the others with this intel.

After careful planning, Yoichi with his squad and Narumi's are to free as many hostages as they can within five minutes while Guren will target the vampire nobles. Ultimately, they are to act as a proper diversion for the main force travelling from Shinjuku. As soon as the five minutes are up, everyone has orders to retreat to the Nagoya Airport immediately.

With the rescue underway of the soldiers tied to crosses outside, Yoichi reports on the situation with Guren's squad as they falter against the nobles. With Yu insisting on rescuing him, and with Shinoa agreeing, they set themselves five minutes where Yoichi is to follow specific instructions for a rescue attempt for Guren and Shinya.

Shinoa Squad fights to rescue Guren who has been captured, and Guren's squad soon joins them. While they rescue Shinya, they are forced to escape, leaving Guren behind. Having fled, after Yu wipes away his tears and states he cannot follow orders, Yoichi and the others are told to proceed without him and he will stay behind. Yoichi along with Mitsuba are shocked by this.

After Yu rushes off to fight Crowley, having followed him, after Kimizuki captures Yu with his Devil's Coffin ability and knocks him unconscious, Yoichi and the squad run toward Shinya, and are ordered to move. Vampire reinforcements are coming. They join with Narumi Squad and many injured soldiers. Running to the airport, when Rika Inoue reports seeing a single vampire straight ahead, the collective soldiers hear Shinya say they can handle one noble and are ordered to keep pushing forward.

The vampire moves through the Moon Demon Company members without killing anyone, and Yoichi recognizes him as Yūichirō's family. Where Shinoa calls out to Mika to little avail as he is set on regaining Yu, while beset by others hostile to him, Yoichi is startled at Kimizuki saying they have to stop Mika before he kills them. As Mika draws near, and Mitsuba who tries to block him is knocked away, after Kimizuki is thrown aside, Yoichi then jumps onto Mika's back as the latter begins to lift Yu from the ground. Stating he is not letting Mika go anywhere, Yoichi says Mika can kill him but Mika is their family so long as he is Yūichirō's family.

Pushed off of him, Yoichi sees Mika has been stabbed by Shinya's bayonet through his back and out his chest. Although Yoichi is praised for his excellent work, he is startled at this scene. After Shinya has been cast aside by Shinoa's cursed gear to get him away from Mika, the squad collectively stand between him and their human comrades. Yoichi says that they have already decided on their motto: "Family takes care of family." The squad then charges at the Moon Demon Company and help Mika escape with Yu.

Shortly after Mika flees with Yu, vampire reinforcements arrive and rain down upon the Moon Demon Company. After seemingly escaping the vampires, Shinoa and her squad, without Yu, run to Nagoya Airport for their rendezvous. While the attacks have stopped, those at the airport observe the vampires are most likely still pursuing them, yet there is no further information on their assignment.

Eventually, a van pulls up at Nagoya Airport where Aoi and Kureto step out. Yoichi shares others alarm at their arrival, and he and Kimizuki recognize Kureto as the one who tortured them. After Kureto orders Aoi to kill the "sacrifices," Yoichi and the squad are ordered by Shinoa to quickly prepare to retreat. As Aoi launches chains from the ground, a pair of chains strike down at Narumi from above, and in the defence of him, Yoichi fires arrows at Kureto.

Commanded to take the curse stimulant pills to help in their escape, as they attempt to survive the chains assailing the surviving members of the Moon Demon Company, the squad has Yu with Mika come to their aid. Vampires led by third progenitor Krul Tepes have reached the airport and clash with the Japanese Imperial Demon Army soldiers. Yoichi is saved from vampires by Shinya, where he and Shinoa squad are told to run while he and the Guren squad backs them. The squad fight their way through the enemies to escape.

With Mirai Kimizuki's body having the Fifth Trumpet active, which has brought the demon Abaddon into the world, as Yu loses control of his Seraph, Yoichi is able to use the scope aspect of his cursed gear to confirm the spiralling column of flames is Yu going berserk once more. Yoichi along with others witness Yu as a seraph defeat Abaddon.

In the aftermath as the vampire forces and army units resume their battle, the squad makes their escape from Nagoya Airport. Spoken on his behalf, Shinoa announces to her squad that they are now seceding from the Japanese Imperial Demon Army. Carrying Yu on his back, yet pursued by soldiers who order that he be handed over, Yoichi and the squad now with Narumi resume their escape with help from Mika.

Three months later, the group is near the sea.

Post-Nagoya Arc
Horsemen attack the village, so with the exception of Narumi, the group fights the monsters encroaching on the settlement. For their efforts they are thanked by the villagers. Where they are unable to help Yu majorly who is turning into a demon for increasing lengths of time, having noticed that Mika drank their blood as the squad approaches him, Yoichi asks if their blood was okay.

In discussing their future plans, which have to take into account Mitsuba's summarization that the Japanese Imperial Demon Army will probably hunt them down and kill them, which puts the villagers at risk, Yoichi also listens as it is mentioned they cannot travel overseas because of how acidic and poisonous the blood-red oceans are. Then, monsters even worse than Horsemen swim in their depths.

They suggest surrendering, although Mika rejects the idea of returning Yu to the army to prevent him from becoming a demon. Makoto is set on saving Yu no matter what in order to give his friends' deaths meaning. Kimizuki states he will do absolutely anything to rescue 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. With Mika's view asked for, he says the vampire queen, his sponsor, participated in the Seraph of the End experiments, so they may be able to trust her. While Yoichi does not have any input into their course of action, neither shares if he has any preference in mind, he is ready for their next objective to rescue Krul Tepes before Yu becomes a full demon.

While the group is on the beach Mika and Yu begin discussing Ferid, the sound of a car engine is heard. Rushing to the roof of a nearby building, Yoichi uses his cursed gear to see Ferid and Crowley driving toward them. Ordered to take their curse stimulant pills and flee, as they run, Yu and Mika discuss their past involving Ferid so 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. With Crowley landing in front of them where he strikes Mitsuba with his sword to send her flying, when Kimizuki asks what they will do, Yoichi responds first by manifesting his bow and saying they must rescue her. After 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, yet his shots are deflected. For the first time, Yoichi summons his demon to the extent curse marks cover his face. After firing again, Yoichi is guided by Shinoa to support Kimizuki. Evident they cannot win, Yu surrenders to Crowley who accepts it and ceases the fight. After Ferid's arrival, Yoichi sees his actions as he presents Akane Hyakuya's head in a jar to them. Additionally, Yu's demon is sent out of control at the sight where he attempts to kill Ferid. After Kimizuki calls for a truce with Crowley and Ferid, the squad departs on a bus with Ferid, and Crowley is driving.

Taking a bathroom break, in the boys' lavatory, Yoichi is present as Yu rants about Guren taunting them with information but never giving them answers. The boys tell Yu to quit shouting, and Yoichi mentions that Yu has started acting like his old self since he received that medicine that Ferid administered to alleviate his demon condition. Yoichi raises how Yu had been acting colder since his demon took over. With the girls entering the boy's bathroom, they discuss their situation as well as the Seraph of the End. Returning 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
After boarding the bus they are driven to Osaka Bay. The group disembark to see an army of foreign vampires before them. While Mika gets information from other vampires, Yoichi is back on the bus and recognizes the two vampires that Mika is talking to one of which is Lacus. Recalling when he killed his sister, curse marks appear around Yoichi's eye as he speaks Lacus' name. Curse marks spread 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, Yoichi faces Gekkouin, who sits on his sister’s bed and leers over the illusion of her corpse. Reminded by Gekkouin of his sister’s death, Yoichi is asked why he is not getting angry. Telling him to stop, Yoichi adds for him to make the illusion go away. When Gekkouin refuses, stating that Yoichi will forget about his revenge if he does that, his response is that he is not running away and points out that even Gekkouin cannot handle all of the high-ranking vampires.

After Gekkouin says he will get help from Yoichi’s buddies, Yoichi replies that he refuses to get them mixed up in his revenge. While Gekkouin speaks that he is being used by Yu for his problems, where Yoichi is being taken advantage of to get his family back, he answers that is completely different. Yoichi explains that Yu is a nice person who refuses to give up and keeps trying to get his family back. That Yu also protects his friends, Yoichi continues 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.

With it pointed out by Gekkouin that Yoichi is implying he is not nice like Yu, this is something he agrees with. Yoichi says he is so mean and nasty and petty where he cannot let the others find out. Detailing the plot to Gekkouin, they must make Lacus suffer and cannot kill him quickly or cleanly. but Yoichi specifies they cannot let his friends know.

Hearing Gekkouin agreeing to help, Yoichi returns to the moment. Asked what is wrong by Yu, but not saying what the problem is, Yoichi replies he is just worn-out before saying he might take a nap. As Ferid and Krul are begin their punishment that second progenitor Urd Geales decreed, Yoichi takes note of the sunlight exposure torture and glances at Lacus.

Taken by Crowley to Ferid’s fifth personal estate in Osaka, Yoichi is still carrying the jar containing Akane's head. Watching Mika and Narumi argue about how the Seraph of the End experiment should not be recreated, Yoichi tries to calm them. At the sudden appearance of Tenth Progenitor Fuola Honte who has exited the mansion, the squad come under attack however Yoichi is unable to fight as he is still holding the jar. After Crowley steps out of the mansion, he is attacked by Fuola only to be beheaded and sliced in half. The group comments on Crowley’s strength. Sparring, the squad learn Crowley's strength is at the level of a seventh progenitor. Since they have decided to rescue Ferid and Krul, they are told by Crowley they must get stronger quickly since they had difficulty fighting a tenth progenitor and must face a fifth progenitor, Ky Luc, who is guarding them.

As the conversation turns to how vampires are former humans, and how they seem like predators, when Kimizuki puts and end to Narumi's line of questioning on Mika's remaining humanity, Yoichi states that species do not matter because humans kill other humans so vampires could be trusted if they did not kill their family. Yoichi hears Mika state his humanity is vanishing but his feelings for Yu have not changed. The rest of the squad enters the mansion looking for food where they are directed by Crowley to the kitchen. After they eat they will be brought into the cellar. With the time having come, in response to Crowley's warning, and Makoto considering that Yu could go berserk in the basement that holds the bodies kept down there, he is asked to give Akane's head to Yu for him to carry. Yoichi accompanies the squad down into the basement and some time later, he is excited to see Guren show up.

When Guren tells Kimizuki that his sister, Mirai, is alive, Yoichi says he is glad for him. He listens to Guren's suspicion that there is a person that has been manipulating the Hīragi Family. For murdering his own soldiers at Nagoya, where Kimizuki and Yu were stabbed, Mika then attacks Guren, which leads to Yoichi with Kimizuki to step in. On one side of Guren, he asks if they can talk this out. 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 after those years, plus will not likely be revived since there probably will not be anything left of her body that was buried. With Mitsuba he then observes an argument between Yu and Mika since the former has decided to go along with Guren's plan.

While Yu works on controlling the seraph with Guren in preparation to fight Ky Luc, with Crowley and Mika monitoring; where Shinoa has joined Makoto and Kimizuki in the library and are trying to read the spell-books there, 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. Heading outside they watch as Yu recovers.

Three days later, Yoichi has Gekkouin aimed at the Ky Luc who remains guarding Ferid and Krul strapped on crosses burning. Counting down from ten seconds, Yoichi fires at the same time as Yu launches himself at the vampire. Barrages of projectiles serve to strike Ky Luc, and also transports UV-blocking bands to the area. Assailments aimed at Ferid and Krul's restraints are also a means to break and free them to allow them to acquire a band.

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, he hears what sounds like a battle. Calling to Kimizuki as he leaves to check his sister, and looking between him and Narumi, Yoichi says he is going with Kimizuki.

Calling his name, Yoichi 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 as it sustains damage from a sudden Hyakuya Sect invasion, where Saitō is mounting a challenge against Shikama Dōji who is possessing Shinoa's body. 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 (Saito) said they should go to Shinjuku. Hearing that Kimizuki means to leave Tokyo and save his sister, Yoichi affirms 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, Yoichi asks what Guren just said when he stated he needs to kill Mirai. He 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 at point blank range 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, before asking why would he 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. Raising 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 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 he going to let Guren get away from him. Instructing Gekkouin to kill him, Yoichi fires anew.

Whilst carrying Mirai with Kimizuki on his back, Yoichi 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. Firing to clear the obstruction ahead as Kimizuki drives towards Yu, he exclaims "yipes!" as they traverse the debris strewn road. With Shinoa's demon used, Yoichi watches open mouthed as she is pulled out of the vehicle entirely. He grabs Mitsuba's leg before calling for Kimizuki, but only manages to seize his glasses. Safe back in the vehicle after being retrieved, Yoichi does not agree with Shinoa's claim that the power of the first vampire is amazing.

Post-Shibuya Arc
Using his cursed gear aim, Yoichi then informs 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 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's behaviour, 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 then raises his hand at Krul's request. When it is mentioned how Shinoa's sister Mahiru Hīragi is involved, Yoichi states he has heard the rumor that she was possessing Guren.

Whilst Yoichi is not seen or heard, Gekkouin was able to gain the power he called Yoichi for in Kiseki-o's realm. Yoichi makes no mention of this exchange with his demon where he stands in the physical world. He is surprised to see Krul reveal Shikama Dōji to be in possession of Shinoa. and similarly when the Lt. Colonel comes crashing into the room, where Yoichi questions how did he find them. With Kimizuki raising Guren's past grievances, Yoichi is of the same mind and has his bow drawn, pointed at the Lt. Colonel behind him. Mentioning how Guren said he had his sister's body stored away too, Yoichi would like to know what that is all about. Questioning how Guren even knows about it, Yoichi asks how much of all this has been a part of his plan. Pinpointing what he would like to know, Yoichi wonders if his sister's death was a part of the plan or not. If Guren says it was, then Yoichi answers that he will kill him.

Happy to see Shinoa regain consciousness, Yoichi listens as Guren asks him and Kimizuki to believe his intent to save everyone. Registering the guilt that Guren feels after causing the catastrophe and lowering his bow, Yoichi along with the rest of the squad are asked to please help Guren. He is surprised that Guren means to resurrect all of humanity. Joining the others on the rooftop, Yoichi mirrors Yu's frustrations at not studying the basics of spell circles back in class. Since he also does not recall the details, Yoichi instead wishes the others good luck as the spell circle continues to be developed.

With Yu having heard Mika calling for him, Yoichi glances towards Mitsuba. He listens as Yu urgently states his need to go wherever Mika is, before witnessing the spell circle activate with a glowing light. As Yu means to use it, Yoichi speaks to remind him that he is family to them too and not to forget that. Joining hands with Mitsuba, he awaits Yu and Kimizuki to join in as well.

While Yu lies unconscious on the spell circle, Yoichi hears the alert from Kimizuki that apparently their demon are collaborating with Asuramaru. Surprised to hear it but understanding what needs to be done, Yoichi's demeanour changes. Confronting Gekkouin in his mind, Yoichi raises that this was not a part of their deal, then questions how he could hurt his family. Grasping Gekkouin's hair to speak face to face, Yoichi tells him he really takes humans too lightly. Explaining that when someone hurts their family they suddenly have infinite desire and greed, Yoichi does not care that Gekkouin has reasons.

Stating that his trust in him is shattered since he dared to hurt his family, Yoichi asserts it is the unalterable truth. If Gekkouin had reasons he should have explained them to him first before doing anything. Regarding Gekkouin's cause, Yoichi questions if he is really that stupid. Reiterating that he does not care, Yoichi is sick of people and their "great cause." Mentioning that they have no cause, Yoichi continues that they as family is all they need. The same goes for all humans and Gekkouin should know that as the demon who has eaten all of his desires. Telling him he is done, Yoichi will hear Gekkouin's reasons and more later, but he will not get one more drop of desire from him.

As Yu remains unconscious in the spell circle, Yoichi observes him, and while kneeling he asks Kimizuki and Mitsuba nearby whether they think Yu is going to be okay. On what Kimizuki means by Yu being addressed as Octopus Face, upon seeing a visual, Yoichi begins laughing. It is recollected that before Yu entered the spell circle he was asked by Guren if he remembered how to subdue a demon, where Yoichi questioned if he would be okay when a reminder was requested. Reacting to being asked if weakening and subduing a demon is what he done, Yoichi replied affirmatively. Kneeling near Yu's unconscious self, Yoichi realizes that a chain has emerged from Kimizuki Passed an injection by Mahiru, he injects it after Saito has relayed his plan where Yoichi considers that Yu and Mika are in trouble.

Using Kiseki-o's coffins, Yoichi joins Kimizuki in reaching Sika Madu's location where he has his bow ready. Calling for Yu and Mika to wake up, Yoichi states they are here to save them. Working with Kimizuki as Sika Madu is prepared to attack, Yoichi answers he sees him then affirms they will stop him for sure. Calling for Gekkouin, he labels Sika Madu a monster and orders him to shut up. If he dares to hurt his family then he will die, and Yoichi follows this up by firing his bow at the First. Preparing another shot, Yoichi is cut apart in the demon world by Sika Madu's scythe. Yoichi is envisioned when Yu is reminding demon Mika of their family.

Recovered and able to move, Yoichi calls Yu's name. After being visualized when Yu is forming his desire to protect everyone, at least two of Yoichi's arrows have struck into the First's back as he and Kimizuki help Yu with demon Mika in assailing Sika Madu. Shouting for Yu to do it, Yoichi then reacts as the seraphs above them emit noises.

Observing Yu with Mika, he is glad to hear the latter has got his memories back and remarks that is great. With Kimizuki he interacts with Yu then asks what are those things in reference to the seraphs. Pointing, Yoichi states they are super scary. Questioning if the First is going to come back, Yoichi asks if it is okay for them to head back to their bodies now. Smiling after being thanked for coming to help Yu, he teleports out the realm.

Gaining consciousness in his body, Yoichi reflects they are finally awake where it is hard to wake while still trying to keep the demons from going berserk. Running over while calling to the Lt. Colonel, Yoichi then turns his attention to Shinoa who Yu has warned is feeling bad. Asking if she is okay, Yoichi has not seen that Shinoa was joking with Yu. After Ferid arrives in a truck, Yoichi is near Mitsuba as he listens while Guren details how they are moving to a new location. Hearing everything concerning the plan will be revealed, Yoichi appears wary.

Sat next to Yu in the back of the truck that Ferid is driving, Yoichi appears happy interacting with others where Kimizuki and Shinoa are opposite him. Finding that Yu is asking Guren about a grand plan he has in the works, Yoichi speaks Yu's name after he mentions if it was not for Guren then he probably would have killed himself. Listening to Yu as he speaks with Guren, he remains a bystander to Yu with Mika clashing against Guren and Mahiru. He considers Yu's words whether Guren killed his family too, and appears apprehensive when the fight resumes.

With the truck having stopped, Yoichi watches Yu and Guren locked together in their fight. Hearing Yu announce that Guren is family too, Yoichi and others are called to agree with him. Happy to do so, Yochi adds Yu said it. Heading to stand before Guren, he is beside Kimizuki as they join hands in the centre. Seeing Guren react, Yoichi finds him joining their hands. After Ferid calls to them, Yoichi turns to him.

Natural abilities
Yoichi has a high innate resistance to the debilitating effects of demon energy, withstanding the auras from a particularly strong cursed gear, Mahiru-no-Yo without any problem. This seems to factor into him being able to form a connection with his demon where he could manifest his own cursed gear without any training from others, which Shinoa observed is something which a normal person would be unable to do. While he is mentally weak, where his lack of strong desires resulted in him being possessed, Yoichi can strengthen himself over time. Indulging in desires to inflict harm on to others also helped get his demon under control, so he did not endanger himself or others in attacking one vampire among many.

This darker side to Yoichi, where he admitted that he does truly seek vengeance for his sister's death, also serves as a determination that fuels and pleases Gekkouin, allowing him to draw out more of the demon's power. Likely drawing on that for other areas, Yoichi is also shown physically 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. The weapon takes the form of a big, black bow with glowing green eye-like features at the upper and lower curves of the bow. A green pentagram symbol that locks and focus on his designated target can appear over Yoichi's left eye. Able to zoom in on a location, it also allows Yoichi to see far away. As well as for scouting purposes, he can readily begin honing in arrows in preparation to be fired. As multiple arrows can be generated, this allows Yoichi to target many enemies as well as seeking them out before they can attack. The spectral missiles themselves are thick and explosive in nature, they fly into a target to bomb them. The avian like manifestation allows this to a greater extent, where the missiles hone in on targets.

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 Gekkouin

"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 Gekkouin.

"Um... I-I'd like it if we didn't have to fight them again."

- Yoichi to Shinoa's squad after fighting some vampires

"...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 Yūichirō'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 Yūichirō! Yūichirō 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, Yūichirō! 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 Yūichirō 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 Yūichirō 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

"Hey, Lt. Colonel? You said you had my sister's body stored away too. What's that all about, hm? You have my sister's body? How did you even know about it? How much of all of this has been part of your plan? Was my sister's death part of it? Or wasn't it?"

- With his bow fixed on Yoichi he questions how involved Guren was with Tomoe's death.

"Really. You take us humans way too lightly. See, when someone hurts our family, we suddenly have infinite desire. Infinite greed."

- Confronting Gekkouin to withdraw power from him after being informed he was working with Asuramaru against Yu.

"Really, Gekkouin. Are you that stupid? I. Don't. Care. I'm sick of people and their 'great causes.' We have no cause. We're family, and that's all we need. The same goes for all humans. You should know that. You're the demon who's eaten all of my desires, after all."

- Not hearing Gekkouin's reasons for his actions and placing the importance of family over people and their supposed great causes.

"I see him! We'll stop him for sure! Gekkouin!"

- Answering Kimizuki's alert that Sika Madu is coming.

"Whatever it is, do it quickly! Shinoa poisoned herself so that she could weaken him. Finish this while it's still working!"

- Shouting for Yu to attack Shikama Doji and revealing Shinoa's assistance.

"Um, by the way? Those things. What are they? They're super scary."

- Asking Yu what the seraphs are and his views on them.

Trivia

 * In the Japanese industry, "Yoichi" is often used for "bow", however 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 possibly changed due to his resemblance of Yūichirō.
 * In the light novels, it is confirmed that Yoichi 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.
 * While not as good a cook as Kimizuki, he can still cook better than Shinoa and Mitsuba.