Satsuki Yamamoto, a teacher at Kairei High School. Satsuki had been secretly living with her student, Tsutomu, in a semi-cohabiting arrangement. When Tsutomu's junior female student, Riho, discovered their relationship, she was shocked. This was because Riho had admired Satsuki as a teacher. As Tsutomu's graduation approached, the three individuals' intentions began to shift...