In order to take care of her nephew, Kosuke, who has lost her mother and is depressed, her aunt, Chisato, decides to stay at home for a while. However, Chisato, who was secretly aware of Kosuke as a man, repeated casual temptations every day, and his crotch was violently stimulated each time. One night, Chisato sheds Kosuke's back ... Kosuke can't control his excitement with his aunt's naked body. Chisato smiles and sucks a cock for the first time when she sees his erected crotch.