A couple who got married with their children. The father had a son, and the mother had a daughter, making them siblings-in-law. One day, the sister-in-law 'Mio' lost her underwear. When she peeked into her brother-in-law's room by chance, she saw him masturbating with the missing underwear. As they struggled to retrieve it, things escalated into rape... At that moment, something was accidentally inserted into the anus...
