義妹のさきはボクのことが世界一好きで好きでたまらない。そんなさきにボクに彼女が出来たなんて口が裂けても言えない…けどある日、僕は我慢できずに家で彼女とイチャついてるのをさきに見られ…「ふ～んお兄たん彼女できたんだ…じゃあさきがぜ～んぶ初めて奪って彼女なんて忘れるくらい夢中にさせたらいっかww」「お兄たん、童貞でしょ？彼女さんのために練習しとこ？」グイグイ迫りくるさきに押され初めてのキスもフェラもセックスまで義妹としてしまった…けど、これは練習なんだ…だから大丈夫…だいじょうぶ…そう思っていたけど…酔った彼女が寝てるそばでもドキドキ背徳セックス！「お兄たん！ダメッ！イッちゃう！！」気づけば妹の虜に…もう彼女には戻れない…「お兄たん、大好きだよ！ずっといっしょにいようね！」

My stepsister Saki is head over heels in love with me, more than anyone else in the world. I could never tell her that I have a girlfriend…but one day, I couldn't resist and she saw me making out with my girlfriend at home…"Hmm, so you have a girlfriend, big brother…well, I'll take all your firsts and make you so crazy about me that you forget all about your girlfriend lol""Big brother, you're a virgin, right? Let's practice for your girlfriend?" Pushed on by Saki's aggressive advances, I ended up with my first kiss, first blowjob, and even sex with my stepsister…but this is just practice…so it's okay…it's alright…or so I thought…but even with my drunk girlfriend sleeping nearby, I was having thrilling, forbidden sex!"Big brother! Stop! I'm going to cum!!"Before I knew it, I was captivated by my stepsister…I can't go back to my girlfriend anymore…"Big brother, I love you! Let's be together forever!"