Suzy and Myungsoo are childhood friend , They always go to school together , play together , study together , and they almost just like Brother and sister . one day ,when they grew up , Suzy say if we have fallen in love , we should share it and tell it , and they promised with their pinky finger .but ,Their Friendship isn't doing work so well as they growing up .because there's a new student from Caliornia , and she's Jessica j