The Royal Family of Nil Kamui was a group of supernautral humans called Koutoushu. They were only partly human though, the Koutoushu provided governance to those blessed by the Red Dragon throughout the centuries. There is currently a group known as the Revolutionary Army who are trying to restore the country of Nil Kamui with the legitimate heir to the royal bloodline, Ibuki. Though is actuality the Revolutionary Army is attempting to place Inori on the throne (as Agito knows that she is alive and has been secretly preparing her for becoming Queen).
Nil Kamui (Nations)

Political Map of Nil Kamui