City Life: Teacher, You're So Mischievous

What happens when a teacher turns bad?

The protagonist is bound to a bad-teacher System. Instead of teaching properly, he starts teaching his students how to do bad things!

The whole school is swept up in bloody chaos, and even the dorm supervisor and the cafeteria ladies aren't spared...

Male student: Who stole the stinky socks I've been wearing for two months!

Cafeteria lady: Which student took my underwear? Want more? Come find me secretly...