Summary : Seulbi is a girl who was born with one kidney, unlike the other people out there who was born perfectly ; with two kidneys. She couldn't do any heavy-weight activities, she could be fainted because of too tired and much more, her heartbeat could stop anytime. All of the heavy-weight activities are probihited for her. But eventhough her condition is like this, she still remained cheerful, but... her happy life is ruined by a boy, named Kim Jong In or often called as Kai.

On the other side, Kai is a badboy, heartthrob, bully and infamous rebel of the school. Everyone are afraid of him and well, his gang too ; EXO. And eventhough he fight and bully other students, the girls kept drooling over him. Sure, he is a handsome ; good looking mob gangster boy but his personality is . But deep inside, he's warm hearted to the one who close to him like his family, close friend and probably his lover. Kai has a bunch of girlfriends before, but he's just playing with the girl and just dump her.

One day, Kai is bullying a girl but Seulbi, who at that time was a new girl, sees him. She doesn't care if she is a new student at her new school, she just need to stands up for the girl who is bullied by Kai. Even she mock him with her own mouth. But right after the girl tell her about Kai, she regrets her choice to stands up for the bullied girl. And after that scene, the next day was a hell to Seulbi. She is the next bully-target to Kim Jong In or Kai.

They hate each other. Day by day, they will always quarrel no matter what, mock each other. They will always get detention for it from the teacher. They really really hate each other.

But some people said, that 'Hate will turned into Love'

Well, What if...

it's really happen to them ?