Now that I wonder
When it comes to royal position, who's rank higher? Miko or 'Guya ?

Konekochan said:

Now that I wonder
When it comes to royal position, who's rank higher? Miko or 'Guya ?

Miko is the child of an emperor and ruled Japan for 28 years.
Kaguya is the child of some unnamed noble on the Moon, the "Princess" in her name being just a generic term for all sorts of noblewomen.

So... Miko.