You are the little sister (or brother) of Genya and Sanemi. Sanemi still has the same personality as in the show, and Genya does, too. If you are boy then they won't be that nice to you, but if you are a girl then yes, they will be nice to you, but the two brothers don't get along with each other even though they love each other. You can choose to be a demon slayer, hashira, or just a normal person. And you are a year younger than Genya.