引きこもりの妹。ボクにとってはただの空気だった。昔から着続けてヨレヨレになったTシャツ。伸びきったジャージ。床に散らばったティッシュとスマホの充電ケーブル。視力は悪いし、人と話すのは苦手。外にも出ないから当然ニートで、いわゆる「喪女」ってやつだ。兄妹だから。だから別に、興味なんてなかった。──はずだった。その日、ちょっとした用事で妹の部屋のドアを開けた。ノックはしなかった。いつもしてなかったから。そこに広がっていたのは、あまりにも衝撃的な光景。妹が、必死にシャツを噛みしめて、腰を浮かせていた。見てはいけないものを見た。一瞬で頭が真っ白になった。何よりもヤバかったのは、その顔だった。普段は死んだ魚みたいな目をして、ぼんやりスマホを眺めているだけの妹が、今はどこか遠くに行ってしまいそうな、それでいて必死にしがみつくような、そんな表情を浮かべていた。理性が音を立てて崩れた。兄としての境界線も、全部まとめて。気づいたときには、部屋に上がり込んで、妹の上に覆いかぶさっていた。抵抗する腕を押さえつけて、震える体を無理やり抱き寄せる。自分でも何をしているのか分からなかった。でも、もう止まれなかった。そして──干物みたいに枯れ果てていると思ってた妹のカラダは、とんでもなく熱くて、濡れていた。我を忘れて腰を動かす。イッてるのに気づかないくらい、ひたすらに、深くまで。「お願い、もう……っ、イってるから……っ」その言葉すら、遠くで聞こえるだけだった。何度も、何度も。奥を穿つたびに妹の指がシーツを掴む。声にならない声をあげて、また小さく震える。それでも止められなかった…

My shut-in sister. To me, she was just air. Her worn-out T-shirt, which she'd worn for ages. Her stretched-out sweatpants. Tissues and a phone charging cable tered on the floor. Her eyesight was bad, and she was bad at talking to people. She never went outside, so of course she was a NEET, a so-called "loser girl." We were siblings, after all. So I wasn't particularly interested in her. —Or so I thought. That day, I opened the door to my sister's room for a small errand. I didn't knock. I never did. What unfolded before me was a shocking sight. My sister was desperately biting down on her shirt, her hips raised. I had seen something I shouldn't have seen. My mind went blank for a moment. What was most disturbing was her face. My sister, who usually just stared blankly at her phone with eyes like a dead fish, now had an expression that seemed to say she was about to go somewhere far away, yet at the same time, she was desperately clinging on. My reason crumbled with a loud crash. All the boundaries of being her brother crumbled too. Before I knew it, I was in her room, on top of my sister. I pinned down her struggling arms and pulled her trembling body close. I didn't even know what I was doing. But I couldn't stop. And then—my sister's body, which I thought was dried up and withered like a sardine, was incredibly hot and wet. I moved my hips uncontrollably. Deeper and deeper, without even realizing she was coming. "Please, I'm…coming…" Even those words sounded distant. Again and again. Each time I penetrated her, her fingers gripped the sheets. She let out a voiceless cry and trembled slightly again. But I still couldn't stop…