Three people who live together with a couple and their wifes younger brother. - The wife had a physical relationship with her husband as well as her younger brother, officially recognized by her husband. - Adhering to the unusual daily life of having sex with a married couple at night and having sex with siblings after the husband goes to work. - Three people who know that they have sex separately but do not see it by implicit rules. - When I get the consent of each and show off the sex of siblings in front of my husband ...