Umi, the younger sister, ends up having a threesome with her older brother and his friend on a whim. She'd always been interested in sex, and had had physical contact with her brother a few times before, but she never imagined they'd be having sex with three people like this... However, seeing two huge cocks ignites her lust switch, and she tightens her mouth and shaved pussy around them, and in the end, they even cum inside her...