My Eternity

The wisteria hashira, (l/n) (y/n) died fighting Kibutsuji Muzan at the age of 16. So why, almost 400 years later, where her and everyone she cared for reborn? And why where they all 15 year olds with magic powers?! But for her and her friends, all that matters, is that there's still a world for them to save, there job isn't done yet!
Kny x reader x bnha