A housewife living with her husband in Tokyo. One day, her husband's nephew, a student taking entrance exams, came to Tokyo from his parents' home. The couple welcomed the nephew, who wanted to stay at their boarding house in preparation for the exam. Miina is a kind, caring, busty housewife who is bad at saying no. The virgin student, who is in the prime of his sexual desire, continues to cast inappropriate glances at the voluptuous curves of his "Tokyo aunt". Then, a few days later, on a night when her husband is away at work, the forbidden first sex takes place...!