[Maekawa Hayato] Onee-chan ga Doppelganger ni Netorarechau! ch.1 [desudesu]

A young boy's late-night confession about his feelings for his older sister is overheard by something wearing his own face, and the doppelganger wastes zero time climbing into Tomomi's bed and popping her cherry in a slick, blood-specked first time while the real brother watches frozen through the glass. Morning brings red rice and a sister who somehow already knows what happened, leaving Aoi to wonder how Tomomi-oneechan could possibly be celebrating—and the smirking double makes it brutally clear he had the balls to do what her little brother only dreamed about. Torn between horror and something hotter, Aoi staggers home to aching balls and a houseguest who has no intention of giving his sister back.