A forbidden physical relationship between a brother and sister who are related by blood. Brother and sister are alone at a hot spring inn where no one knows them. The younger sister, Yuuki, is so happy to be able to spend the whole trip with her beloved brother that her vagina is always wet and slippery. The brother embraces his sister whenever he has free time, and the horny sister climaxes, her delicate body twitching. The brother plans to develop his sister's erogenous zones on this trip and turn her into a semen toilet that will obey any command. *There are no performers under the age of 18 in this work.