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 The quiet and withdrawn sister, Mayu, inevitably depends on her brother for both playmates and sex partners. When he thrusts into her small, narrow pussy while playing with her nipples, her sensitive body trembles as she climaxes in agony. She is trained to be an obedient sister who squeezes out every last drop of her brother's sperm after it is ejaculated inside her. *There are no performers under the age of 18 in this work.