Misaki and her son, Koichi, are habitually involved in an incestuous relationship. The reason is that Misaki's husband is completely unable to get an erection. One night, Misaki begins masturbating alone while her husband sleeps beside her. Her actions excite him, and he starts touching her, but no matter what he does, his penis remains limp. In the end, she has no choice but to call Koichi to come over.