Koushi Nagumo

Koushi is quite responsible and mature for his age. Even after being abandoned by his father, he fell into depression and tried to look for a job. When he started to work as dorm mother, even though the girls were older than him, he didn't hesitate to scold them. He even tries to warn them to be more aware of how they act and dress as he is still a boy and has desires.

(Source: Megami-ryou no Ryoubo-kun Wiki)