Yuri, the mother-in-law with a birthday on the same day as his wife and enormous breasts. The son-in-law Yoshinobu accidentally gives Yuri the erotic underwear meant for his wife. Seeing Yuri start to masturbate while wearing the underwear, Yoshinobu's desires are unleashed. "You're actually frustrated, aren't you, Mom?" Yoshinobu relentlessly pursues Yuri's enormous breasts everywhere without getting caught by the family...
