Jinnosuke Mudou

無堂仁之介

He is a guest instructor in the test prep class that Itsuki Nakano have attended.
He was the former teacher and ex-husband of Rena Nakano, thus being the biological father of the Nakano quintuplets. He holds some animosity towards Maruo Nakano because of allowing his daughters to follow the same misguided path as did his late wife.