A boy falls to his death at school, but Ok Chanmi does not believe that her twin brother, Park Wonseok, committed suicide. Chanmi transfers to her brother's school, Yongtan High, and meets Ji Sooheon, who witnessed her brother's death.

It depicts the story of Lee Seung Min, a boy with zero presence who is offered a contract relationship by Oh Ji Na, the best girl-crush idol trainee in the school.