While I quoted the entire sentence, my interest was in the claim that "the current ruling race in Hingashi are the Raen". Which would mean either the Mitsurugi clan or the imperial family, depending on the view one takes of it.
In regards to Yuki Yatsurugi, while hime is often localised as princess, it does not necessarily indicate that the individual is the daughter of a monarch in Japanese use. In this case, presuming hime (姫) is used and not oujo (王女), or I suppose denka (殿下) if she's part of the imperial family, it is more than likely meant to indicate that Yuki Yatsurugi is simply of noble birth.
The Auri (and Hyuran) enemies are ronin/shinobi hired by Kageyama for his takeover of Kugane Castle. The Au Ra also Xaela for some reason.
