For crying out loud, another fantasy setting that is actually Earth in the far future. I hate when writers do this, and that it's especially so prevalent in Japan. It's not a fancy twist, it's a trite cliché that knocks a work down a few pegs in my eyes. Fantasy can stand on its own, no need to lessen it by tying it to sci-fi. Whatever, I'm still enjoying the story, so I will keep reading.
Sorry for the rant. It seems like the no-armed superpowered people are becoming more common these days. I don't have anything against it, as it's still an interesting concept to work with, and this princess has potential, too.