Kokubu

国分

Kokubo-sensei is the head teacher at Hinata Kawamoto's middle school. He also acts as the interim homeroom teacher for Hinata's third-year class, 3A, whose female bullies are infamous for driving their original homeroom teacher to a breakdown, which led to her resignation.
Kokubo-sensei's effective initial step to combat the psychological contagion threatening to engulf the entire school is to disband its source, the gang of girl bullies, by reassigning each to a different homeroom.
Before relinquishing his post as class 3A's interim homeroom teacher, Kokubo-sensei has several philosophically interesting heart-to-heart talks with the recalcitrant lead bully, Megumi Takagi.