17 AB Abnormal Class 13 Shori Wanizuka or rather Koi Munakata.

Munakata is a member of the 13th party and part of the Flask Plan. Although he acts calm and reserved most of the time he always has the huge urge to kill people, due to his Abnormality. Munakata says himself that he doesn't kill without reason, it's more like all reasons are good enough for him to kill someone. He's on the nation's most wanted list.

(Sources: Medaka Box Wiki)