A stiff cock, even in old age, changes the fate of a happy family. Jun lives with her husband and elderly father-in-law. One day, while caring for her father-in-law, his penis becomes erect. Although he is disabled, his penis unintentionally becomes erect, and the kind Jun considerately takes care of him by providing sexual relief. It had been a while since she had sex with her husband, and before she knew it, her crotch was wet and she was lewdly sucking her father-in-law's penis in her mouth. The two escalate their infidelity amid the conflict of family love...