Na Bori was a legend in high school for being a troublemaker and getting into fights. Then one day she gets expelled from school for being involved in a fight. After overcoming numerous hardships, she gets a job as a substitute teacher at her old high school. She is excited with the fact that she will be able to meet her old teacher, Ji Hyeon-woo, whom she has had a crush on for years. But a troublemaker in her class, Tae-in, keeps getting her into trouble. Tae-in is a smart and an athletic student. From Tae-in’s point of view, he dislikes Bo-ri because she isn’t smart but at the same time, has a headstrong personality. As his relationship with his teacher turns for the worst, he gradually becomes attracted to her through a series of complicated events...