The forbidden physical relationship between siblings connected by blood. A brother and sister alone at an unknown hot spring inn. The brother, who usually has sex with his sister and ejaculates inside her, decides to train her for anal sex to avoid pregnancy. The obedient sister reluctantly accepts anal sex for the sake of her beloved brother. The shaved sister, whose vagina and anus have been developed by her brother, and a one-night-two-day incestuous hot spring trip.
