Mirei, a housewife living with her husband and daughter's family of four. Although she leads a life without any worries, she was having an affair because her nighttime life with her husband had become distant. One day, Mirei accidentally discovered a video featuring her son-in-law, Yoshihiro, at a love hotel. Intending to ask Yoshihiro about its authenticity for her daughter's sake, Mirei ends up having her own affair discovered. "If you want to have an affair, let's do it with me!" Yoshihiro forcefully demands it with his young dick. Yoshihiro's lust for Mirei, who is his mother-in-law but has beautiful skin and plump huge breasts, doesn't stop, and the two continue their affair within the family...