「乳首オナニーばっかりしてると、乳首が石みたいに硬くなっちゃうぞ」兄がついた嘘がきっかけで無知な妹が大暴走！硬くなったらまずいとお兄ちゃんの男性ホルモンを膣で吸引！生ハメセックスの気持ち良さを知ってしまった妹はお兄ちゃんが「イッちゃう！」と言っても「もう中に射精してるって！」と言っても夢中で気付かず杭打ちピストンしまくり！中出しを完全スルーして溢れ出る精子を気にもせず更に腰の動きを加速させる！

"If you keep masturbating with your nipples, they'll become as hard as rocks," her brother lied, which triggered her naive sister's wild behavior! Fearing that her nipples would get hard, she sucked her brother's male hormones into her vagina! Having discovered the pleasure of raw sex, the sister was so engrossed that she didn't notice when her brother said, "I'm going to cum!" or "I've already ejaculated inside you!", and continued to thrust away! Completely ignoring the cum that was spilling out, she didn't care and accelerated her hip movements even more!