One day, when I was starting to think about getting married to the girlfriend I was living with, her younger sister Ria came to stay over. - She is a little natural, but Ria-chan is an innocent and beautiful girl who doesn't even look like her. - Moreover, she is not easy to push, and since she is a cute girl, you can do whatever you want! - When I was secretly having sex with her without telling her, she suddenly awakened to eroticism and on the contrary, was asked for it every day and was fucked!