Awesome, Okinawa is fun. I'm assuming you're being stationed there by the military? I lived there for a year (MCAS Futenma) from 04-05. If you like to go out and have a good time, you'll love it!!
I got a car for free while I was there. It was a pile of crap Toyota Corona. As bad as I wanted to get a skyline, I couldn't justify spending money on something fun like that when I knew I was only going to be there for a year. There's tons of cool options for cars there.
Just like others said, it's not true that they are required to take cars off the road due to milage. How it worked when I lived there, was if you bought a car brand new, it was good for 5 years. After 5 years, you have to get it inspected every 2 years, and you pay for the inspection. They go over the entire car, and if they find something wrong, they require you to repair it before they re-license it for 2 more years. So as cars get older, and start having issues (even just leaks), they get costly and difficult to relicense. So people end up just getting a new car. That's why you end up with lots of low mileage spare stuff from there.
My free car was never going to pass another inspection. It was good up until about a month before I left when it expired. So on the day it expired, we went and kicked the crap out of it for a half hour, then I drove it to the junk yard
Only picture I can find of it. This was right after we got done kicking the shit outta it.