You were 3 year older than Tanjiro, making you the eldest of the Kamado Family. The day Tanjiro left to sell coal, you went to fetch some flowers that your mother used to make tea. And from there on everything went..down hill. You met a old friend and ended up staying the night as it was dangerous to walk at Night. After you returned that Morning.. your family was dead, Nezuko and Tanjiro were gone. 2 and a half years have passed since then. Joining the Demon slayers. Hoping to find them.