Heisuke Hara is a teacher at a Buddhist boys' high school in Shizuoka, Japan. His school is facing a crisis due to a declining student population and is planning to merge with a nearby Catholic girls' school. Having experienced a traumatic incident in his own youth that involved both schools, Heisuke is tasked with facilitating the merger and managing the first-ever co-ed class. The series follows the chaotic and comedic attempts to integrate the two student bodies, who harbor deep-seated prejudices and rivalries against one another. As Heisuke navigates the cultural clashes between the Buddhist and Catholic traditions, he must also confront his own past regrets and help his students find common ground, leading to unexpected friendships and budding romances.