Amber is a girl who studies in an all boy's school which expertise in sports. Her dream was to become a famous runner in that school but she couldn't take the chance to train because of her fatigue body. And the problem is that the competition that she was supposed to participate in was coming to a close. Her only hope was her sister, Eunhee, who looks like her and who has the same age as her, to replace her position for the competition. The problem is, Eunhee wasn't like her sister who is like a tomboy but she then agrees in taking her sister's place.

Eunhee doesn't know anything about the school and her sister's best friend until a student helped her around. Little by little she was starting to have feelings over the student, but little did she knew that the student was Amber's best friend.