Death Game Manga no Kuromaku Satsujinki no Imouto ni Tensei shite Shippai shita

デスゲーム漫画の黒幕殺人鬼の妹に転生して失敗した

One day, Mai remembers that her perfect stepbrother is a character in a death game manga, and that one year later he will hold a death game involving all of his classmates, killing his sister in the process.