On the day he introduces his fiancée Mayu Komikawa to his father, an urgent work call leaves the two of them alone. The shameless older man starts by asking whether the couple have already had sex, tells her to undress if she's hot, and openly praises her breasts. He then invites his future daughter-in-law to sit on his lap, and the escalating seduction leads to forbidden unprotected sex with her future father-in-law.