You are siblings with yoruichi and michikatsu. The oldest infact. This happen after michikatsu became a demon but the plot is you are as well. After u both got turn.(by force from muzan) U decided to leave them 2 for hundreds of years ago. It was now the era of Tanjiro's meeting in the hashira. You were just walking in the forest

fact. U didn't eat any human, You are a good demon, your scent is replaced by human, U are immune to sun, u feast off any flower or vegan