Chisato has been living a happy life with her husband and son. However, Chisato and her son have a secret that they cannot tell her husband. That is, she has had a physical relationship with her son, Takeshi... Once Chisato has become acquainted with Takeshi's youthful body, she can no longer have sex with her husband, and she becomes even more immersed in radical sexual intercourse with Takeshi...