While her husband is away, a man claiming to be his colleague suddenly appears and exploits a weakness in the Higuchi family, setting his sights on wife Mitsuha. The couple had been deeply immersed in nightly sex, happily trying to conceive. However, the husband began making repeated mistakes at work, all due to exhaustion from their intense sex life. The man threatens, "I won't get your husband fired—but let me fuck you once." Mitsuha firmly refuses. But the man relentlessly pursues her, licking her, seducing her, and ultimately inseminating her completely.