Kim Jongin is a lucky man. He's got a girlfriend who adores him, a nice house, and a cushy new job as a special forces detective.  But there's something that has been eating Jongin away for the past 10 years: the disappearance of his childhood best friend, Do Kyungsoo. 

Song Narae is a poor scholarship student attending Seol Chong Academy, the most prestigious prep school in Seoul.    Kim Jonghyun is the sole heir of a corporate mogul and the most popular guy at Seol Chong Academy. 

With the death of her mother, Tarian's world is turned upside down. Denied by her adoptive father's family, she is sent to live with her biological family in Seoul. There, she's forced to settle in with a new family, in a new town, at a new school, with new people.  Although settling down is

Jinri is something of a home-wrecker.  It's not that she does it on purpose. ...

Jiyong hasn't seen or heard from Eunmi in over two years, so he doesn't expect a midnight phone call from her to change his entire life.  But it does. 

Bang Yongguk is the epitome of cool, so the last thing he wants to do is spend his senior year of high school hanging out with some dorky middle-schooler. But, if he wants to graduate, that is exactly what he's got to do. 

Risae has given her everything to the person she loves, but sometimes that's just not quite enough.    (Xiumin-centric!)