Hijiri and Arisa are a new couple, having a study session at Arisa's house. Arisa's mother, Yurika, is kind and beautiful, wearing clothes that emphasize her chest, and even knowing she is Arisa's mother, Hijiri can't help but get excited. On his way to the bathroom, Hijiri catches Yurika intensely masturbating. She calls out his name while playing with her vagina, fully transforming into Arisa as she masturbates. Watching his mother-in-law's masturbation, he also strokes his erect penis, but fails to ejaculate and ends up frustrated. He returns to the room in a sullen mood, unable to think of anything but Yurika.
