Yoshihiko lives with his wife Haruka and her parents. With the shift to teleworking, Yoshihiko is spending more time with his mother-in-law Chisato, who he never had the chance to be alone with before. But then Yoshihiko is gradually drawn to Chisato's adult sex appeal! Taking advantage of the fact that his wife and father-in-law are not around, he approaches Chisato and squeezes her obscenely big breasts. Eventually, the act is carried out by the family, and the affair within the family becomes a quagmire... The son-in-law is turned on by Chisato's ripe body, which is more mature than his young wife's, and Chisato also finds pleasure in sex with a cock younger than her husband's...