The Mihara household consisted of a wife, her husband, and his father, living together peacefully. However, they struggled for years to conceive a child, causing mounting stress and despair. The wife confided in her father-in-law, who had many siblings, and speculated that his sperm might be strong. She eventually begged him to impregnant her. Initially, their arrangement began as a clinical, emotionless duty, but gradually, she became deeply addicted to the sexual encounters with her father-in-law. When she finally confirmed her pregnancy, they agreed to end their secret affair. Yet after giving birth, unable to resist their desires, they resumed their forbidden breeding sessions once again... A delicate and complex story depicting both the warmth of family life and the unexpected shifts in relationships.