BLK-630 My little sister, who recently debuted as a gal, chose me, her brother, to practice sex. The two of us, still lacking knowledge about sex, are engaged in an uncontrollable double piston motion. Sumire Kuramoto

My sister decided to become a gal. Once she becomes one, she has to be flirty, so she starts practicing sex! And the partner chosen for this is me, her brother! I've watched AVs, but I don't have any practical experience either... But if I can't do it right on 'that day,' it'll be embarrassing, and I need to maintain my dignity as a brother. So, we practice piston movements together! Maybe because of our blood relation, our compatibility is superb! We're both incredibly virile; it must be genetic! Without realizing that the other has already climaxed, we continue with reverse flow and double rampant pistoning, culminating in a massive internal ejaculation!