Why are there so many mixed people in okinawa?

Question:

i went to okinawa on a trip and like there were some japanese people who looked mixed with white. there was one girl in a store i saw who was speaking japanese and she looked like she was black and asian. is there a lot of military relationships in okinawa?
I mean its not like I saw mixed people everywhere, but i did notice some people every now and then and it made me curious.

Answer:

Theres a lot of US military base in Okinawa.
I have 2 friends who are from Okinawa and one of them is mix of japanese and black and she speaks japanese and english both fluently.
The other one is mix of jap and white and she speaks a lil of japanese and fluent english.