The Kobayashi family lives together with their daughter-in-law, husband, and stepfather. However, she was worried about not being blessed with children. Her husband has many siblings, and she suspects that her father-in-law's sperm is strong, so she asks her father-in-law to impregnate her. Her daughter-in-law, who initially intended to start her business, gradually became absorbed in sex with her father-in-law. When she found out she was pregnant, their relationship ended.
