Mari (Aoi) had grown distant from her husband in the bedroom, and unable to endure the physical discomfort any longer, she found herself resorting to masturbation. She became so addicted that she couldn't calm down without masturbating every morning and evening. One day, as Mari headed to the bathroom in the morning, she encountered her son Satoshi leaving with his crotch in hand. Suspicious, she pulled down his pants and discovered he was suffering from a severe morning erection, painfully swollen and unable to relieve himself. Seeing her son in such distress, Mari reached out to touch his groin in an attempt to ease his built-up tension. That act triggered something unexpected, and from the next morning onward, Mari began making her way to her son's room each day.