invayne
Kana and Ceilie background and the reasons they hate humans was pretty good and it made sense why they bonded so quickly, but I can't say the same for this princess. I'm assuming the princess is a child, provably barely 13 since you failed to give her an age. But even if I consider her a small and naive child, the plot is too forced. If her maid was already brought by one of her siblings then she wouldn't allow the kid to run away, you already painted her as naive so she would be easily coaxed to give up these plans, even talking to one of the siblings or father. And they wouldn't allow her to escape and get so close to the border. It would've been better if you made the princess smart, cunning, hateful of royalty and humans after seeing her mother murdered and the indifference of a king, after seeing how greed and uncaring the servants are, after suffering abuse and humiliation once her mother was gone, but not this naive child who can be easily manipulated and has no sense of danger sleeping through the entire night attack and explosion. There's no reason to root for her or hope she becomes non-human, no reason to want her in the party.
This is slowly becoming predictable and feels super forced. I mean, come on. They JUST met the princess...and suddenly trust her so much and want to help her in her quest? Let's not forget Kana has led a life full of abuse previously and Celia has more than her fair share of human-induced trauma as well. The backstory you gave both characters makes them trusting the princess and jumping on the bandwagon after like half a day INCREDIBLY unrealistic.