Wasn’t he an English teacher tho? Like I do know of one where the teach goes on rampage just cause he’s a psycho, and lock down the school doors and shit and tries to kill his students. And he was like pretty charismatic so he was pretty much loved by everyone but he was blackmailing behind the scenes.
The most I remember from this manga is mack the knife references and the movie version of the teacher going "Magnificent" so yeah I don't remember the subject he taught. It was a really good manga though other than the fact the killing was a bit too brutal.
Is it that one perhaps ? http://www.mangago.zone/read-manga/aku_no_kyouten/
Yep its this one thanks
Guys wasn't there a manga about a mathematics teach killing everyone of his class at a school?