Maiko, a mother, lives with her daughter and son-in-law, who are worried about her husband living alone after his husband is transferred away from home. On the surface, their relationship is good and there are no problems, but her frustrations are piling up and she indulges in masturbation every night. Then, her son-in-law, Hikaru, secretly peeks at her lewd behavior... When Maiko finds out that Hikaru has a big dick, she can't control her overflowing carnal desires and seduces him obscenely at every opportunity. The son-in-law's huge cock swells up as he watches his mother-in-law's repeated lewd behavior, and finally he can't hold back...