The two recently became brother and sister after their parents remarried. Asuka, the older sister, found out that her younger brother is a gloomy guy who isn't popular at all, so she tricks him into drinking a super erection drug that she happened to get her hands on, but... he unexpectedly awakens his sexual prowess! The drug works too well and she is attacked and given a blowjob... her still-horny brother has sex with her at night... she secretly gives him a titty fuck in the family's room... he breaks in while she's taking a bath and they take a mixed bath... he pistons her with an endless creampie! The older sister keeps shaking her hips even after her horny brother has lost all sense of reason, and they experience nonstop orgasms!