>Sasanohara Shiori is a childhood friend of the protagonist Yuichi. She is a strong-willed and nagging woman. >Yuichi and Shiori live in the same neighborhood and have played together since they were children. >However, Shiori has a secret that she cannot tell anyone: She is half human, half succubus, and has a constitution that requires her to consume semen regularly. >Succubus go into heat and crave semen when they reach puberty, so Yuichi has sex with her to suppress her heat and gives her semen. >One day, a playboy who Shiori's mother knows starts living in their house. This catches the eye of Shiori, who then enters her room without permission and has his penis pressed against her, causing her to go into heat.