Yumi (Yumi Kazama), who majored in humanities at a certain famous university, is a wonderful woman full of intelligence. There was a time when she aimed to study various literature, but now she is married and has a son who is a high school student. One day, her son Tomoki brings his friend Takeshi to stay at the house because he wants to study. Yumi, who likes young and cool Takeshi, is stimulated by the sadistic part inside her as she watches him struggle.