Wretches

Wretches (Korean: 괴물들; RR: Goe-mul-deul) is a 2018 South Korean drama film written and directed by Kim Baek-jun.

The movie with someone entering the school after hours tapering a student locker.

Yang-Hoon (Lee Yi-Kyung) then takes over his #1 position at school.

Yang-Hoon harasses Jae-Young (Lee Won-Geun) and it gets worse.

One day, Yang-Hoon, who has a crush on Bo-Young (Park Gyu-Young), gets Jae-Young to follow her.