My younger sister, a schoolgirl, is taking a nap with her panties exposed. The older brother was excited by the sight of his sister's panties, so he immediately grabbed his dick and had sex with her. However, he is soon noticed and treats the older brother who lusts after his girlfriend's younger sister as a pervert, but he gradually begins to feel sorry for her. The younger sister is tired of her older brother who is unable to cum even though he offers to help her...!