Wretches(2018)

Original title: 괴물들

Jae-young is a high school student who is often bullied by the school’s mob leader, Yong-gyu. When Yong-gyu is hospitalized, Hoon wants to take his place at the top of the school. Jae-young hoped doing away with Yong-gyu would help him escape the tedious violence, but he finds himself tormented and harassed even more under the persistent Hoon.