Her nephew Toshiki suddenly decides to stay in her apartment, Sayuri, who has suddenly moved to Tokyo from the countryside, and begins to clean her room in a panic. Before the cleaning was finished, the doorbell rang out at the entrance and Sayuri came. Toshiki is surprised by Sayuri's youthful appearance after a long time. "For the next three days, I'll be alone in my small apartment with such a beautiful aunt..." As I was thinking about this, Toshiki's lower body began to go out of control, contrary to my rationality...