The Morisawa family, where the wife, husband, and father-in-law live happily together. However, troubled by not being blessed with children, she consulted her father-in-law. Although her father-in-law couldn't find an answer, the wife, who thought her husband had many siblings and that her father-in-law's sperm might be strong, ends up asking her father-in-law to inseminate her. The wife, who initially thought she was starting it as a job, gradually becomes addicted to sex with her father-in-law. There was a promise that their relationship would end if a baby was born, and when she found out she was pregnant, their relationship ended. But after giving birth, the two of them, who could finally no longer stand it, resumed insemination intercourse…