Okinawa

I would like to go to Okinawa and the rest of the Ryukyu Islands because of their distinct history from the rest of Japan (they were once a separate kingdom) and I want to visit the historic castles there. But my grandfather tells me the stories of US servicemen who were harassed by the locals because other servicemen raped Okinawan girls. So I'm curious for two things: 1) What is there to do in Okinawa? and, 2) Do they really hate US visitors?