Emi teases her unpopular younger brother as a joke. The virgin brother takes the joke seriously and thinks she is trying to seduce him, so as soon as their parents leave, he inserts his penis into his sister. Emi climaxes from the force of the thrusts, but her brother, who is not used to women, ignores her and continues to thrust his hips recklessly. Even after climaxing, the pleasure of the thrusts continues, making him climax over and over again, and despite his resistance, he continues to cum until his parents return home.