A couple living happily together suddenly had the husband's NEET brother kicked out of his home and come to stay with them. After sending her husband off to work and finishing the housework, Arisa secretly masturbates in her room. However, she is seen by her brother-in-law, who asks for her body just once; embarrassed, she agrees. This act becomes a catalyst, and from the next day on, it escalates—she lets friends' penises be sucked, plays remote-controlled pranks beside her husband, and more. Though troubled, she finds herself drawn to her hypersexual brother's lust.
