Han Serim is feared by everyone due to rumors that she is a gangster. Kang Seung-woo, the 'perfect student,' ends up in a mentor-mentee program with her and tries to get close to her to maintain his perfect record. But what is up with this girl? A dangerous and unpredictable romance between Han Serim, who lives as if there is no tomorrow, and Kang Seung-woo, who plans his life down to the last detail.