Female teacher Hana is living with her husband and his younger brother. Coincidentally, she also serves as the assistant homeroom teacher for her brother-in-law's class. One day, she receives a request from her brother-in-law: 'I want to know about women's bodies.' Although confused, Hana decides to fulfill his wish by using her own body to provide sex education as both a sister and a teacher. However, the sex education gradually turns into incestuous sex…
