A decade ago Kim Jaejoong lost his mother, Jung Yunho lost his sister and Shim Changmin lost the girl he loved. 10 years later, you arrive in their lives.   Will you to be solution to their miseries, or the source of new trouble?

Everyone in school knew Lee Soomi, the hot chick in Grade 12-A who screw up Biology with attractive marks in Physics and Chemistry. But no one, not even her boyfriend, Kim Yohan knew about her deep crush on her Biology teacher, Oh Sehun the guy who was already engaged. 

During a party, Sehun found himself doing something completely out of his character; make-out with a random but hot stranger. With his one-night fling now a nice but distant memory, he begins his senior year of high school ready to become a slave to studying. There's a problem, however, when he meets Kim Jongin, his new, young, hot teacher. The same man he had a fling with at the party. After trying to deny a connection and attraction Sehun and Jongin find themselves in a forbidden romance; d

Miyoung wants nothing for her last year of high school to be as successful as possible. However, things complicate when her tutor abruptly takes leave. Replacing her old tutor is Byun Baekhyun—the young, bright-eyed substitute teacher Miyoung finds herself falling in love with despite her best knowledge. It’s a tragedy in the making, but it’s always hard to look away from train wrecks as such.

Do Kyungsoo was expecting a quiet stay in his last year of university but his husband Kim Jongin, a dance professor, decided to surprise him thus chaos ensuing, jealousy emerging, and schedules getting messed up.