Little Sister Downgrade

It's been four years since Miya's stepfather married her mother, and every day since then he's taken her body by force. With her mother turning a blind eye to their comforting new life, Miya makes a wish on a tanzaku slip hoping that instead of a gross old man, she'll get a cute little sister she can play with. As her stepfather wakes up in the body of a young girl, Miya's wish comes true, and it's about time she has her fun.

(Source: Fakku!)