Three days of absence of parents who lived in sex with a sister-in-law.

Five families of three married couples and three children (wife from the wife, a boy from the wife, and a boy of a college student from the wife) who remarried with each other's attendants surround the breakfast. My parents went to travel to Atami for three days from noon. When the son who came back home in the evening is relaxing, the younger sister of the younger sister enters the room and comes to the gutter, and the next day, another younger sister, and the 3P life with the sister-in-law sister begins...