Satomi Usui and her husband, unable to conceive, begin treatment at a fertility clinic. After counseling, the husband is sent to a separate room while Satomi undergoes a gynecological examination. The doctor is stunned by her extreme sensitivity and, going far beyond a standard exam, secretly inserts his penis and ejaculates directly into her vagina. Satomi gradually becomes aroused by the act. During her next appointment, the stimulation grows even more intense, and she finally becomes addicted. With her husband right next door, the thrill and pleasure consume her, transforming her into a lustful, unfaithful wife. The overwhelming shock and ecstasy she experiences profoundly shake her mind and soul.