You were my first love.

Kim Min-gyu and Yeo-ju were friends since birth, but they broke up when Kim Min-gyu transferred schools in high school. At the time of their breakup, Kim Min-gyu liked Yeo-ju. A few years later, Yeo-ju and Kim Min-gyu, a new employee at a large corporation, meet again as assistant manager. Kim Min-gyu remembers Yeo-ju and hits on her every day, but Yeo-ju finds it annoying because she doesn't remember him, but she gradually starts to remember him.