My OC × demon slayer

when kenji urokodaki trained with her father, she found out she wasn't very good at water breathing. so she escaped and found the flame hishara. wanting to give the most painful death to demons. she trained with the oldest rengoku and eventually both her and koujiro rengoku and kenji urokodaki, became hisharas. the flame hisharas. this was the first in century's because there was only ever one flame hishara.
as she grows, so does tanjiro kamado and suddenly kenji is getting flashes of the future. could she protect the ones she loves?

I don't own KNY
if you have any ideas tell me, I be running out of ideas real fast this is also just for me so sorry If it don't make sense.