Park Sooyoung, is 18 year old undercover agent, posing as 18 year old Kim Haera. Her mission is to find the members of Fireflies, hiding in Seoul High School. She soon finds them, but unfortunately, she has already fallen in love with one of them. What will happen to her?

Yoo Ara looks like a normal 17 year old girl, but behind her mask lies a deep scar. She always gets into trouble and fights, not normal ones though, and gets chased by gangsters. But she always had her gang. But after an incident happened, she left her hell. She wanted to forget everything. But....Can she run away from her past? Or will her past chase her?  

Three times they met. They were considered enemies. What was worse than that is the fact that she had to see his freakin face every single day. What sins did she commit to have him in her life?  She wished he didn't exist He wished she would dissapear from his life forever ... Or so they thought