(This is in the Infinity Castle)

You were her older sibling by 9 months. You were a few years younger than Kanae (your guys older sister) though and she took care of you and Shinobu when your parents were killed by demons in front of you 3. When Kanae died from Douma {Uppermoon 2}, Douma took you with him and personally turned you into a demon. You’re now an Uppermoon.

However, Shinobu became the Insect Hashira. One night, all the Hashiras, plus Genya, Tanjiro, Zenitsu and Inosuke (minus Rengoku and Tengen) were all falling through the Infinity Castle. While Shinobu was falling she caught sight of you, who is now an Uppermoon. You don’t remember her at all..