Desugeemu manga no kuromaku satsujinki no imouto ni tensei shite shippaishita (Associated Names)

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. Mai plans a variety of surprises for her stepbrother every day based on what he said in…