A pair of siblings on a family hot spring trip. The sister approaches her brother, who is struggling with being uncircumcised and a virgin. In the mixed bath, she asks her big-breasted sister, "Could you please pull back the foreskin and wash it for me?" Will the kind-hearted sister wash her brother's penis and help him lose his virginity? Although confused, the sister carefully pulls back the foreskin and washes it. Seeing this, the brother's penis becomes fully erect! Seeing the impressive penis after the foreskin is pulled back, the sister's vagina starts to throb. The aroused siblings secretly engage in forbidden deflowering and continuous internal ejaculation without their parents' knowledge.
