Yu, who graduated from the national literature department, was aiming to become a literature researcher for a while.She married her husband, whom she met while she was in school, and now has a son who is a high school student.She lived a noisy but peaceful life, but one day, her son brought her friends and held a study session for her.As she spends time with her young, muscular son's friends, Yuu's hidden sadistic personality begins to throb.So, Yu plans to teach her not only school studies but also sexual things.