Someone by the name of "That XX" has been slipping little love notes into your locker. Yet, for three months, you have no idea of the identity of your mysterious secret admirer. So what will happen if you do find out?

Horikita Maki is pretty much an average girl but she has a really hot brother, YunHo whose in the famous boyband, DBSK. Maki and YunHo are really close siblings. One day, Maki's parents told Maki that they have arranged a marriage for her. Maki, who was still a high school student, doesn't want to get married to someone she doesn't love, decided to run away from home. She approached YunHo for help and offered to let her stay at the DBSK dorm.

Maki and Hiro are really close brother and sister. Their parents passed away during a fatal car accident. Their company was handled by Hiro and thus, he always had to move around and does not have a stable home. Maki is also transferring school. One day, Hiro told Maki that he had to leave for America for some business-like matters. So as not to affect Maki's studies furt