Botchan (Kazunari Ninomiya) has sense of strong justice and does not lie. He is offered a teaching job at a middle in a small village far away from his hometown of Tokyo. Botchan accepts the position and begins to work as a math teacher. The assistant principle there wields absolute power. Botchan has a hard time dealing with his fellow teachers and the students.
All Yuan Zhinan has left behind when she passed away is a letter and an invitation to a school reunion. Attending the reunion in lieu of her late elder sister, Zhihua accidentally runs into Yin Chuan, on whom she had a crush in her youth. As old memories are evoked, and correspondences travel through different contexts and times, Zhihua slowly uncovers the intricate story of the trio.