[Amuai Okashi Seisakusho (Hoshino Iro, Kikkomuhito)] Imouto Work [Full Color]

A horned demon girl has already claimed half her victory—her hero opponent wakes to find a brand-new body, complete with a soft, heavy chest that keeps getting grabbed and a skimpy outfit held together by little more than ribbons. When the flustered hero gambles on a contest of endurance, promising to outlast the teasing succubus at her own game, the demon gleefully accepts, dangling the cruelest stakes imaginable: lose, and she becomes a little sister forever, never to be a hero again. Tongues and trembling thighs tangle between striped stockings as both girls fight to hold out, with the demon savoring every shuddering gasp on her way to a permanent family addition.