Minami lived happily with her beloved husband and daughter, but it became a habit to masturbate at night without any help. And the same went for her son-in-law, Tsuyoshi, who spent his days comforting himself by looking at her. Minami, who was fascinated by his huge cock, made his heart flutter and continued to seduce him each time. The son-in-law could not resist his mother-in-law's invitation, and one day the two of them fought back and forth day and night.