Naoki Shinoda is the protagonist of hentai. He does all the chores and cooks for his single mother, Arisa Shinoda. Naoki's parents divorced when he was still a child. Her father cheated on Arisa, but she did not forgive him. With child support, Naoki's mother bought a new apartment, which was located next door to her childhood friend Shiori Nishimura. They lost touch with each other during their school life. But now they are close again and share snotty memories with each other. One day Arisa decides to go on a big trip, Naoki sets the table and he and Shiori celebrate her departure. During the feast, Arisa asks her best friend to take care of her beloved son. Shiori soon catches Naoki masturbating while watching porn. She hasn't had sex for almost ten years. So she decided to train Naoki a bit and satisfy her own at the same time.