OBD-073 My son's virginity was taken by my mother-in-law

Nanao lives with her husband, mother-in-law, and 24-year-old son. Speaking of dissatisfaction, it's about being sexless with my husband for 20 years. My worries are that my mother-in-law has recently started to be senile, and that my son is still a virgin. A severe earthquake ran through such an ordinary family! The stupid mother-in-law told her son, "Grandma will teach you," and took her virginity. Nanao witnesses the scene. She masturbates to calm her strange excitement, but she can't let her excitement cool down and finally puts her hands on her son's body!