After discovering that his younger sister's body had grown into "an adult woman's body" without him knowing, her brother has been teasing her and playing with her body as a tool to release his sexual desire. It's a dangerous relationship where he twists his big dick into her mouth and thrusts it into the back of her throat, and thrusts into her tight pussy and casually creampies her, but his sister Yura, despite seeming to dislike it, is a super perverted girl who gets her pussy wet and shakes her hips.