Even amidst the awkwardness, erotic tension explodes in this forbidden sibling taboo game! Though they have no romantic awareness of each other, they play along as if they’ve already hooked up. Gradually undressing, both end up flashing their panties. Using a help card, the brother shares a kiss with his sister, while desperately trying to hide his erection, his face betraying an embarrassingly aroused expression. The sister checks his state directly—though only borderline aroused, she judges it barely acceptable, driven by the prize money. Next, the brother gives his sister a denma punishment; her smug expression quickly shifts as the inexperienced virgin brother delivers overly intense shocks, making her twitch and squeal while barely holding back pleasure—though the result is clearly a fail. Meanwhile, the brother is now fully erect. As punishment, the challenge "Make your brother’s cock go limp!" is issued. Ignoring her brother’s obvious discomfort, the sister boldly takes his cock into her mouth and immediately starts aggressively sucking with deep, skillful oral action—no hands, just her mouth. Unable to hold back, the brother cums inside her mouth. Yet his cock remains rock hard, so the sister resumes fellatio. With no sign of softening or another climax approaching, the brother nervously asks to penetrate her. Hesitant at first, the sister—overcome by excitement and the thrill of losing her virginity to her brother—straddles him and gently guides his cock into her pussy. Despite being mindful of him, she rides him hard, climaxing repeatedly from the raw sensation of her brother’s cock. She then requests missionary, getting pounded intensely as they make love like lovers, screaming orgasm after orgasm. The brother, reaching his limit, spurts a creampie inside his sister without permission. Rather than getting angry, the sister eagerly accepts his still-hard cock from behind, losing herself completely—her face twisted in a shameless ahegao, grinding her hips back on her own brother as she cums again and again. A second creampie follows. Completely exhausted, her body and pussy spent, the sister gives the brother’s unrelenting cock a handjob, bringing him to his fourth cumshot of the day.