Su Gan

Han Su Gan is a school bully who mercilessly abuses his victims. He can make anyone his target for torment, because he will face no consequences. His stepmother is very wealthy, and if Han Su Gan kills someone, he will be covered up without question. All the teachers and the principal turn a blind eye to his antics.

Han Su Gan has his own company.
With whom he abuses innocent people. A girl named Lee Yu-mi, who is part of the bully's group, films all the abuse. Cha Woo-min, a boy also from the bully's group, helps him beat them up, just like Su-gang. Lee Ji-woo, a girl from the group, also films everything, just like Lee Yu-mi.

You're the new girl who transferred to this school. The class monitor told me not to talk to you or get caught in his sight if I want to finish school peacefully.

One day you saw Han Su-gan dragging a girl by her hair. And everyone just ignored it.