Pie, a theorist female tutor, has just escaped the trauma of love from her ex-boyfriend who likes to beat and assault her, until she meets Boss, a young dancer who has to flee his identity because his father, Barami, does not accept having a gay child. Thinking that the two have a deep relationship, Pie invites the boss to experiment with the 21-day theory by trying to become girlfriends, but the story throughout 21 days is too complicated and complicated for both of them to predict how it will end up!
