Hourai42 He beat their motherfucking asses bro. Just wait till Heejin tries some other shit and gets shot in the face =P. And anyway, he can't just beat the shit out of a girl in plain sight. Fighting the brother was the smartest decision to make. Not only will he be seen as a dick for fighting Heejin by all bystanders, he'll also be seen as a woman beater and he'll probably go to jail for assault on 7+ people, including a 2+ women (which will be even worse). Plus Kim Kinsoo or whatever seems like he has privileged parents from how the cops handles the sister's case. Protecting his sister instead at school is admirable to other students and won't be seen as aggressive or as intentional harm by other people since it was a reaction to a situation and not pre-planned.
Anyway, I like the story and I'm looking forward to more. If this gets cancelled, I'll cry. He'll probably mask up and do some stuff in the shadows or call in on his connections to get something handled. If not, fight lol. Just fight.