"You are too late. Someone has replaced you since years ago, since you decided to leave me." "Can we just turn back the time? I'm still in love with you. Those memories, do you still remember them? Can we rewrite the present and the past?"  

Choi Hyo Soo, an innocent and lovely girl has became Jongin's closest friend ever since they were children. Believe it or not, there's never only "just friend" between a boy and a girl, so did them. Their relationship contains love, accidentaly love. How if..one of them made a mistake? A really big mistake that make both of them couldn't be together anymore? People said that love has its power. Sure it is, but does the power of their love strong enough to face the reality?