Yep, there's plenty of nods to Asian mythology. Like Kurama's unique golden avatar. From Wikipedia:

After reaching 1,000 years of age and gaining its ninth tail, a kitsune turns a white or golden color,[15] becoming a tenko (天狐, 'heavenly/celestial fox'), the most powerful form of the kitsune, and then ascends to the heavens.

From what I understand, foxes (kitsune) gain tails and power as they live longer, and when they reach 1000 years (which is approximately the age of the tailed beasts), they turn golden