We were in Okinawa last fall on the Regal Princess. Four of us rented a car in Naha, where the ship docked, and drove around the southern end of the Island. We visited Castles and War Memorials. If you wish you can go to Photo Galleries and see some of my pictures we took while there. Look under RayB and find the pictures.
Naha is a very modern and interesting city. You should enjoy.