Yes this book is the ship Flarie x Origami Katana but it is of course Fantasy AU and humanized, so they have human names for this one.

Flarie - Flare

Origami Katana - Ouka (this is the only thing I could came up with since there is the meaning about cherry blossom so yea-)

Warnings:

Dark themes
Small bits of cursing (like a few times or so in every chapter)
Gore (we'll get to that in further chapters not at the beginning)
Unexpected plots (I know you'll hate me for this-)

And that's it without furthermore, we'll move on to the beginning.