'Senkōki'

"M'name is 'Senkōki'. It's m'job to make straight, pretty holes."

- 'Senkōki', introducing himself to Mikoto Suoh.

 'Senkōki'  was a male Strain held within the Usagi's Nanakamado Chemotherapy Research Center as a criminal charged with multiple accounts of murder. He was simple-minded, yet aggressive, and lived to fight. Throughout the novel, his "name" appears as 'Senkōki'.

Appearance
'Senkōki' was a large, muscular man with short, light hair and blue eyes.

He wore little clothing, and only wore a pair of dark pants.

Personality
'Senkōki' was simple-minded and aggressive. He was said to have killed many other Strains, and took great joy in fighting strong people. He made "innocent" expressions - mostly smiles - that didn't fit his intimidating appearance.

He spoke simply and childishly, often about how he would never stop fighting, and even referring to his constant fighting as his "job". Given his simple speech, he was a blunt, honest man.

In combat, he was extremely aggressive and relentless, and intended to always kill his targets. Along with this, he never evaded attacks In his battle with Mikoto Suoh, he expressed discontent when not being acknowledged. Nonetheless, fighting was his primary source of joy, even in death.

History
'Senkōki' had murdered many Strains, and earned the nicknamed "Strain Killer". At some point, he was apprehended by the Usagi and taken to the Nanakamado Chemotherapy Research Center. He likely underwent many of Kōshi Mizuchi's experiments to test out the limits of his own abilities and Mizuchi's regenerative factor.

Mizuchi uses 'Senkōki' as a way to deter Mikoto, and the two's battle stems over a considerable amount of time. It isn't until Mizuchi's regenerative ability starts to lose its effectiveness that Mikoto eventually defeats him. Even when 'Senkōki' is seriously injured, he declares that he will keep on fighting to the end. Afterwards, Mikoto burns him to death from the inside, starting with his heart.

Strain
Enhanced Strength: As a Strain, 'Senkōki' possessed immense strength. He was capable of punching a hole through any surface.