During summer vacation from university, I visited my relatives' house and there was my grown-up cousin, Sayaka-chan! She still treats me like a child, and her defenseless breasts and ass are too erotic! What's more, when I decided to stay overnight, Sayaka-chan came to me, who couldn't sleep because I was horny! When I can't stand it and attack her, my cousin's sexuality, which she had been suppressing in the countryside, overflows and we end up having sweaty sex...