Daijirō Kutsuwa is a teacher in Kiri Kato's middle school who orchestrated the bullying on Kihara and then, Kiri.

He's a middle aged man with a black, closed shaved hair style and a goatee styled beard.

He's a cruel man who wishes to get rid of any delinquents regardless if they changed or not.

Manga Debut: Chapter 157 (The Ninja, the Demon, and the Red Horns)
Anime Debut: Episode 75 (SOLITUDE)

(source: SKET Dance Wikia)