After her father-in-law died, her daughter and her husband Kazuya, who were worried about her mother-in-law Madoka, decided to live together. At first, they were nervous about each other, but now they've opened up to each other. One day, Kazuya witnesses her Madoka masturbating. Kazuya, who can't help but feel horny, masturbates using her girlfriend's panties. However, that figure was found by her mother-in-law, Madoka.
