Hajin, a North Korean middle school girl, comes to South Korea to do homestay at the house of Woooyoung who is same age with her. Losing his own room, Wooyoung works on the project to send her back. However, he unintentionally falls in love with her and even runs away from home by leaving for Seoul to help Hajin who wants to meet her father. This makes them separate again but after a long waite, Wooyoung's pure and dearest wish comes true.