The daughter of a policeman, Koito Matsuda, holds a strong conviction that humanity holds an innate purity and despises dishonest ways. On her initial day at secondary school, she encounters Taiga Akiyama, who due to repeating a year, had earned a reputation for his troublesome behavior. Nonetheless, Koito persists in her belief that he is a decent person and endeavors to assist him in assimilating into their class.