Mitsuki is jokingly teasing her unpopular younger brother. Thinking that she is really inviting him, the virgin brother inserts his penis into his sister right after their parents leave. Mitsuki climaxes from the force of it all, but his brother, who is not used to women, doesn't notice and continues to thrust his hips frantically. Even after he climaxes, the pleasure continues to chase him as he continues to climax, and he keeps climaxing until their parents get home. "I've already cum...!!" his sister screams, but Mitsuki completely ignores her and makes her climax over and over again with his wild thrusts!