My beautiful older sister, who was once a shining example, has now become a single, unemployed, and unmarried woman in her late 30s. After a failed marriage, she moved back in with our parents, where she spends her days playing erotic games, accumulating pent-up sexual desires, losing her sense of ethics, and awakening her erotic side. Now, she's using me, her younger brother, as a tool for her sexual gratification, and I don't know what to do about it...! - Kanamori Morisawa