Japan have been paying generously and fully for USA military presence. They even buy junk pork like F35 which are only minor updated F16 if different frequency radars are used.
Okinawa kingdom was found by Japanese in 1100s. “The Chūzan Seikan (1650), the first official history of the Ryūkyūan Kingdom(Okinawa), and Chūzan Seifu (1701) state that Shunten was the son of Minamoto no Tametomo (1139 – 1170).”
Part of reason Okinawan don’t like base by main city is they are reminder long occupation and rapes and atrocity by USA. “village in Okinawa where GI’s raped every woman, girl, and child”
However, majority of protesters seem to be mainlanders. Some are Japanese communist who are probably funded by Chinese spies trying to espionage. Other might be greedy people who were probably promised piece of hydrate money when okinawa becomes independent.