Yōhei Nasu

, also referred to as or , is a first-year at Ishiyama High School and the former head of Sōrei High School. He is also the leader of a musical band of students known as the Poltergeists.

Appearance
Nasu is a very tall, lean-built and muscular young man with droopy eyelids.

He possesses blond hair and gray eyes. Particularly, his frizzy hair is predominantly swept back, causing most of the strands to shoot up.

Nasu wears hoop earrings on both ears and he also has a round stud piercing on the middle of his tongue. He has a preference for wearing different kinds of necklaces; currently, he is shown to have at least two, with one being dark and holding a cross pendant, as well as another chained necklace that has a round pearl-like object on the end.

His usual outfit consists of the uniform worn by the Ishiyama High School males, which is a combination of a dark-colored jacket possessing five round buttons, with long sleeves and a short collar, as well as dark-colored pants. Nasu usually wears a light-colored shirt underneath his open jacket. Currently, he is shown wearing a horizontally-striped shirt, as well as one having a distinctive dark bull's eye, where Nasu's left pectoral muscle will be, with a light-colored arrow below the design pointing up to it. Nasu also wears light-colored shoes. Underneath his shirt and jacket, Nasu is shown to also wear light-colored tassels each connected to a small suction circlet attached to his pectoral muscles, just above his nipples.

Nasu has recently obtained three childishly-drawn whisker markings on both of his cheeks after Baby Beel drew on them with a marker. He left the markings on his face for some time before finally removing them.

Personality
Nasu has a cheerful, carefree and somewhat flamboyant attitude. He often jokes with others even after provoking them in a certain nature, which is heavily evident with Nasu's habit of sticking out his tongue and squirrel-like grin. However, despite Nasu's genuine demeanor, he can be very sarcastic to the point where it becomes mocking; nonetheless, he retains a cheerful attitude and is depicted as being childishly innocent when doing so occasionally.

Nasu's inner and darker demeanor is shown to be rather arrogant, intimidating, and especially vicious. He once coldly tells two of the "Three Kings" that there is such a difference between them in strength; afterwards, he proceeds to violently attack them so as to further prove his point. His remark towards Akahoshi and Ichikawa, as well as his further attitude towards Oga in their second battle, shows an additional arrogance and superiority complex in Nasu's personality. He believes himself to be a capable and dominant leader who, as expected of someone like himself, should "reign" over their Demons and their gang with utmost power, as it supposedly means everything to them; additionally, this shows that Nasu holds a certain amount of confidence and faith in his gang. As such, when he finds that his superiority and leadership is being challenged or shadowed over, he begins to feel shocked and even scared of the stronger individual. However, his most prominent emotions during this crisis are frustration and rage, especially when he feels that regardless of the situation, he should be in a stronger position than the other.

History
Nasu was a student from Sōrei High School before he transferred to Ishiyama High School. During his time there, he became the head of the school.

Sometime before attending Ishiyama, Nasu came into contact with the Solomon Company. He was later contracted with a Demon who is among the Seven Deadly Sins, notably being one of three, the others being the rest of the Three Beasts, who were able to handle them.

Return to Ishiyama High School Arc
While Nasu is sneaking up behind Kanzaki and his gang, he is unexpectedly punched by Oga and sent crashing into a concrete wall, effectively being buried within it. However, sometime before he is hit, Nasu manages to draw over Oga's Zebul Spell tattoo, referencing his name in it. After some time, he starts breaking free from the concrete wall until he is finally released from the hard material, albeit with a large chunk of the building destroyed and a smaller portion stuck around Nasu's neck. He introduces himself to Kanzaki and his gang.

Nasu immediately targets Kanzaki and begins attacking him with a whirlwind of powerful kicks; eventually, he deals a hard blow to the third-year, which renders him unable to continue fighting any further. Nasu stands over the defeated Tōhōshinki and mockingly asks whether someone like him is actually very weak and pathetic. Bored, he tells Onizuka that he can fight one of Kanzaki's underlings as long as he goes easy. Later, after Shintarō Natsume demonstrates his raw strength against Onizuka himself, this brings excitement to Nasu and he requests that they "play" together. He is refused, however.

Nasu does not become disappointed due to Oga's and Baby Beel's unexpected arrival which immediately draws in the former's attention. When asked about the markings over Oga's tattoo, he admits that he may be responsible; however, after Nasu then revealing his name and leadership status to Oga, he asks whether Oga liked his "autograph", indirectly confirming that he is the one who drew on Oga's Zebul Spell. Moreover, Oga's punch has made it tiring for Nasu, which is why he left a marking afterwards. After his cheeks are unexpectedly drawn over with, he is told that he can give Oga a free punch for earlier; though he admits that it is a bad idea, Nasu goes ahead and punches Oga anyway, forcing him up in the ceiling and burying him in the concrete. Nasu smiles gleefully upon his action. He proceeds to mockingly ask Oga whether he is still alive and later if he can even hear his voice.

Shortly thereafter, two of the "Three Kings", along with their respective gangs, arrive in the hallways to confront Nasu: Ebian Ichikawa and Kankurō Akahoshi. Nasu tries reasoning with them both until Oga, who is still stuck in the ceiling, speaks out that he will beat up all of them. Nasu sarcastically tells him to speak up. Instead, Baby Beel pops out from the ceiling and angrily points at the delinquents below. Ichikawa comments on how cute the infant is; likewise, Nasu also finds the infant to be cute, and he shoots an intimidating smile at Baby Beel. Moments after, Oga breaks free from the ceiling and lands on the ground, holding Baby Beel in one hand. The child-rearing gang leader asks how much Nasu knows; due to the vagueness of his question, Nasu instead asks about what he is referring to.

Before either can say anything else, Ichikawa suddenly slashes at the concrete around Nasu's neck, cutting it into several pieces and moreover rendering Nasu free. When Ichikawa and Akahoshi start fighting each other, they are stopped by Nasu who, evidently "awake" now, slams them both on the ground. He tells the two "Kings" that the differences between him and them is wider than the Grand Canyon. Before anything else happens, Oga punches the wall and destroys a large chunk of the building, annoyed that they have seemingly forgotten about him. Nasu is impressed by Oga's strength and mentions how it must be because of the child on him; dismayed about not having one himself, he complains loudly.

Suddenly, Shioiri and the other Poltergeists arrive in the hallways; apparently, Nasu has missed band practice today. Nasu exclaims how they've come to pick him up and tells Oga that they will have to put their battle on hold for the time being. Before he leaves, he tells Oga that they will target everyone who came back from Saint Ishiyama, and that he will personally see to Baby Beel being taken away from his adoptive father.

After some time, Nasu tells the other Poltergeists that they will take down Oga and his friends tomorrow during fifth period.

The next day, while inside a seemingly empty room, a shirtless Nasu stretches his arms with a flower in his mouth and tassels dangling from his pectoral muscles. When Hajime Kanzaki and Takayuki Furuichi suddenly burst into the room, where they discover that the other Poltergeists are present, Nasu gleefully greets the two delinquents. Nasu tells Kanzaki that the reason why they are all there is because they are the Poltergeists, referring to their sudden appearances as "magic". The insignia of Nasu's Demon then appears as he says that.

Nasu stands by and watches as Kanzaki attempt to knock out Shioiri, only to be pushed back and be stomped on his stomach. He looks at Kanzaki's seemingly defeated body and mocks Oga for being a "bad leader" despite having Baby Beel. Nasu is then told by a bloodied Kanzaki that he shouldn't underestimate Oga. Suddenly, Oga then bursts through the door with Baby Beel on his shoulder. Nasu tries to tell Oga that he can only make that sort of entrance so many times; before he can finish speaking, he is told not to underestimate Oga's Kamikaze captain, since he is not yet defeated.

Soon afterwards, a King's Crest imprints itself on Kanzaki's back, which causes Nasu to feel surprised that Kanzaki is able to gain it without knowing of its true power. Subsequently, a female individual explains about it to him and the rest of the delinquents inside the classroom.

Nasu later approaches Oga and Baby Beel on another side of the classroom. Nasu listens to Oga as he repeatedly asks him questions, particularly on how he is supposedly a Demon Contractor, though Nasu remains silent for the most part. He eventually speaks up, noting that Oga has been asking a lot of questions, though he adds that he will not answer any of them; instead, Nasu clarifies that he is actually a Spell Master. While a confused Oga reflects on his words, Nasu temporarily immobilizes him, then allows himself to repeatedly attack Oga with a series of punches. However, he also ends up receiving a punch which causes Nasu to crash into a cupboard. Nasu licks the blood running down his lips as he continues to lie against the destroyed wood.

He soon rises up and swings his arm, which subsequently creates two identical clones of himself appear before Oga's eyes. Using the clones as a diversion, Nasu then proceeds to attack Oga with a kick and a punch, knocking him a fair distance away. Nasu scolds Oga for his arrogance on seemingly knowing about spells properly and states that he will show him the correct way to utilize his Demon's power; as he says that, his tattoo develops into several identical insignias across Nasu's body, which moreover channels his Demon's power and creates a Magic Seal around his body. Nasu uses many comparisons for his use of Spells as he proceeds to violently attack Oga; during the midst of it, he tells him about the superiority they should have over their Demons, adding that if he were to be given Baby Beel, he would use the infant's power to the last drop. As Oga lies nearly defeated at Nasu's feet, he attempts to explain that the Poltergeists were never a match for Oga's gang.

However, Nasu then realizes that his own gang has just been single-handedly defeated by Kanzaki, causing him to shudder and begin to sense fear.

During so, he sees Oga rise up and utter "Father Switch", then Nasu receives a hard punch to the face. The impact of the punch, as well as the troubled thought that the other Poltergeists have been defeated, begins to enrage Nasu, and he even asks about the "Father Switch" that Oga just mentioned. Nasu calls Oga out as a cheater during the fight but still continues to attack him; however, as he learns about the meaning of the "Father Switch", Nasu ends up receiving a beating instead, which angers and frustrates him further. At the brink of defeat, he is left wondering why Oga's fists feel so heavy against him.

Nasu suddenly feels an overwhelming sensation overcome his body; realizing who is behind this unsuspected event, he angrily wonders why that person is doing it to him. He ends up creating nearly thirty clones of himself and eventually explains to Oga about the Spell; moreover, now that it has been enacted, Oga shouldn't stand a chance. Nasu becomes angered again when he hears Oga's nonchalant remark and violently attacks him with the other clones. Unfortunately, Oga drinks from his canteen of milk, which subsequently causes him to enter Super Milk Time, and he rapidly punches Nasu and his clones into the ceiling. Nasu thinks in utter shock that Oga and Baby Beel can merge bodies as he and his clones are buried into the ceiling.

The effects of his Spell, Doppelgänger, quickly wear off.

Powers & Abilities
Nasu holds a considerable amount of pride and self-confidence in his Spell Master powers, claiming that he can properly use them. When he begins to use his Demon's power, root-like black markings expand from his Spell Master insignia over his left pectoral muscle, stretching across his torso and arms, until several matching insignias imprint themselves over his arms and chest. Moreover, a glowing Magic Seal, which resembles a ring with several relic symbols found inside them, envelops near him. Nasu releases a vast amount of Demonic power when he first uses his abilities that it can notably corrode the tiled floor of a classroom inside Ishiyama High School. It is later revealed that his Spellmaster abilities were rooted from being contracted to one of the Seven Deadly Sins. Which of the Sins, if he knew of this, and if he is still connected to the Demon is unknown at the moment.
 * Immobilization: He creates an Emblem underneath his opponent's feet, which prevents them from moving.
 * Dispelling: Nasu uses his Spell Master powers to create four Emblems; when surrounding a similar insignia, namely a Zebul Emblem, it causes the aforementioned insignia to dissipate and dispel its properties.


 * While moving his hands and fingers intricately, he creates three Magic Seals directly in front of him that create a straightforward pathway. Nasu then runs through them, granting him a significant boost in speed. When using this spell, it also appears to grant additional effects on Nasu's fists; when he uses this against Oga, both of his fists become enveloped in a light, which moreover destroys parts of the Magic Seals that Nasu previously summoned.


 * One of Nasu's most prominent techniques; however, it appears as though Nasu requires a significant amount of Demonic power channeled into his body before he can use Doppelgänger with mass results. Nasu uses this technique to create multiple real-life clones with apparent physical and mental capabilities, equivalent to that of a Human's. Evidently, when the spell loses its affects, the clones melt away in a dark liquid. Nasu is able to replicate and control at least twenty-five clones of himself in one sitting.

Hand-to-Hand Combatant: Nasu's most preferred method of fighting, with or without additional support from his Spell Master powers, is general martial arts. Nasu is shown to be a very capable fighter with an unorthodox style based mostly around punches and kicks. Using his particular speed and flexibility, he can easily can easily overwhelm formidable opponents, particularly those of Hajime Kanzaki's and Tatsumi Oga's caliber. He easily defeated Kanzaki, who is a fighter well-known to use a drop kick style, with just a few powerful kicks to his body; moreover, while performing such kicks, Nasu is able to use both legs while midair with very accurate coordination, despite the fact that he would be unable to see his feet in the position and situation that he is in. In a related fight against Oga, Nasu kicks Oga a fair distance away, only to jump back on him with a powerful punch. Regarding punches, he is also rather skilled in the style. He is able to deal a powerful uppercut to Tatsumi Oga and literally bury him in the concrete ceiling from one of Ishiyama's buildings, showing relative ease upon conducting the act. In a continuing battle, Nasu has been shown being able to conduct multiple punches to his body in a very rapid amount of time before Oga could react.

Enhanced Strength: Nasu's body is noteworthy for being very tough and resilient. As such, his hand-to-hand combat techniques are considerably stronger than that of an average Human's; this is especially proven with his rapid number of punches and kicks during one sitting. Moreover, despite his head being buried through a concrete wall, he is able to push himself out, as well as destroy a large portion of the wall without further inflicting any damage to his own body. Nasu can also easily flip over two teenagers close to his own size using only two hands, one for each.
 * An evident rip-off from a technique in Fatal Fury, particularly from the playable character Howard Geese, as noted by Akahoshi. Nasu grabs the fists of two people and as he moves his arms, only to then swing them down in a cross-like formation, he flips the two people over and slams them on the ground.

Enhanced Speed: His range of speed is more advanced than that of a regular Human; when in a more normal situation, he is shown to be abnormally quick, especially proven in a fight against Tatsumi Oga. He instantaneously moved back to Oga's side after having previously kicked him away. His speed is more notably exemplified in his use of punches; during his second fight with Oga, he rapidly punches the latter on several occasions, all of which within a short matter of time.

Enhanced Flexibility: Nasu, even without the use of his Demon's power, is an unusually flexible man which has proven to be a strong point in his equally-unorthodox method of fighting. Additionally, a relating attribute to his flexible body revolves in his body movements, which are evident to be particularly carefree and loose.

Tatsumi Oga
After experiencing a trademark attack from Oga first-hand, which Nasu later regards in the same light as one unfavorable, he has since looked down upon the child-rearing gang leader; as a result, he often speaks to him in either a very sarcastic or mocking manner. He considers Oga to be a bad leader, due to apparently being unable to keep his fighters as strong as they can be, which Nasu believes is evident in Kanzaki. Nasu also finds himself to be superior than Oga when it comes to strength; therefore, when he begins to lose against Oga in their second battle, he becomes frustrated and enraged.

Baby Beel
Nasu displays an unusual but intensive interest in Baby Beel, which is explicitly stated when Nasu says that he will take the infant away from Oga, then proven true when Nasu states that he will continuously use Baby Beel's power to his own liking, should he have access to it. Nasu particularly thinks highly about Baby Beel's powers and bemoans the fact that, while he himself does not have such an infant with him, the one that Oga has appears to be wasted upon him.

He also considers him to be very cute and has nicknamed him "Lil' Beezy".

Quotes

 * (To Tatsumi Oga): "From here on out, we're gonna be taking down all you guys from Saint... and in the end, we'll take that baby from you."
 * (To Tatsumi Oga): "Sitting on the throne means dominating everything. That goes for Demons, and your crew too."
 * (To himself): "What the...!? What's going on here!? Why am I the one looking up at him!!!?
 * (To himself): "Why!!? Why am I getting tossed around like this...!!? By... someone who can't even use spells properly... How the fuck am I getting my ass kicked like this!!? Is it because of our Demons? No... As far as I can tell, my power is a lot stronger than his... not to mention that I'm the one using it properly!! ...So why? Why is the weight of his fists so fucking heavy?