My beautiful aunt comes to stay at my apartment...

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...