Sister is a doctor, younger sister is a nurse. The two beautiful sisters somehow encounter "erection boys" who expose their hard cocks at a high rate. The elder sister, who loves her younger sister, continues to masturbate the erection boys with her fingers and tongue to protect her younger sister from them. But the younger sister gets excited when she sees a hard cock and can't help but service it with her mouth... Today, too, the sisters might be licking the cocks of strangers or patients!