Before being turned into a Next-Level Villain, Kirihito Kamachi was a regular person. From what little is known about him before his transformation is that he had the face of a thug. He has prominent cheekbones, a bit pronounced sharp teeth, flat nose, eyes without pupils and lacking eyebrows, sticking-out ears and short and pointed black hair.
After being kidnapped and modified by bio-engineering, and his quirk was was boosted and pushed to the limit, his body acquired physical characteristics of a mantis. While his chest remains mostly humanoid, although with insectoid characteristics, the lower part of his body has a mantis abdomen and four legs similar to the said insect. His arms became scythes-like limbs, and although his face remains the same, now he has chitinous protuberances and a pair of antennae.
According to his friends Ichiro Hotta and Jiro Hotta, Kirihito is not a very smart guy, who, despite their warnings, liked to consume the adulterated Trigger that for months was distributed on the streets and caused so much trouble. Despite this he's really not a bad person, and actually has a lot of intelligent things to say about society and the way mutant Quirk users are treated. He laments his new mantis form, seeing it as nothing but a hindrance to his daily life.
Due to his new appearance, he is especially susceptible to people prejudging him and treating him like a villain due to his mutations, yet he quite hypocrite because he has no problem to do the same thing to other people with mutated bodies, which is lampshaded by others.
Likewise, he seems to be a person of refined tastes, enjoying tea times while listening music, and he values good manners and respect for personal privacy.
Enhanced Strength: After being modified by the Villain Factory and doped with large doses of Trigger, the strength of Kirihito is considerable, to the point that it is capable of destroying the concentre of the streets with his scythes-like hands. Even so, he is easily defeated by Captain Celebrity, and once he stops taking Trigger, his strength is considerably reduced.
Enhanced Speed: Like his strength, Kirihito was given augmented speed when he was turned into a Next-Level Villain, to the point that he was able to match Koichi's.
Unnamed Mantis Quirk: After being bio-engineered into a large humanoid mantis with very sharp claws; when boosted by Trigger this Quirk makes Kirihito much bigger and sharpens his claws.
Kirihito is a person who liked to consume Trigger. Although the Hotta brothers warned him to keep away from the more suspicious drugs and tried to dissuade him to buy the new adulterated version, he ignored them. The Villain Factory, responsible for distributing the adulterated Trigger, saw potential in his Quirk, and decided to kidnap Kirihito and experiment on him.
Time later the Factory release him in the streets of Naruhata. Kirihito, already transformed into Next-Level Villain, is rampaging when The Crawler confronts him. However, the vigilante is overwhelmed by Kirihito's strength and speed, and the villain chases the boy down the street. Captain Celebrity arrives and easily defeats the villain.
After spending some time in prison, he is released and all his charges were dropped after the police learned that he was a victim, since the Factory bio-engineered on him. However, when he returns to his apartment, he discovers that he can’t get in the place because his new body is too big. Therefore, the Hotta Brothers decide to welcome him and let him live in his warehouse. Naomasa Tsukauchi and Shota Aizawa goes to the Hotta brothers' shop to meet with him and talk about his kidnapping by the Villain Factory, but the only thing that he wants to complain is about how today's society discriminates against those who are physically different, like him. The others consider that he just exaggerates too much.
Some time later, Kirihito gets involved in a fight against Octoid, another Next-Level Villain, which had been attracted to the warehouse where he lives by Shota, Koichi and the Hotta brothers. Kamachi faces Octoid, but since he no longer consumes Trigger, he is much weaker that before, being overtaken by Octoid. Fortunately the others intervene and manage to capture the Next-Level Villain. However, another entanglement with Kirihito release Octoid by accident, who escapes, only to being found afterwards badly wounded for unknown reasons.
Kirihito has a good relationship with the brothers Ichiro and Jiro, who call him Kamayan affectionately. The brothers care for him and help him whenever they can, but they recognize that he is not very smart, and that he tends to exaggerate his complains.