Directly south of Naha in Kaigungo-kōen is the Former Japanese Navy Underground Headquarters, where 4000 men committed suicide or were killed as the battle for Okinawa drew to its bloody conclusion. Only 250m of the tunnels are open, but you can wander through the maze of corridors, see the commander's final words on the wall of his room, and inspect the holes and scars in other walls from the grenade blasts that killed many of the men.
To reach the site, take bus 55, 88 or 98 from Naha bus terminal to the Uebaru Danchi-mae stop (¥220, 20 minutes, several hourly). From there it's a 5-minute walk – follow the English signs (the entrance is near the top of the hill).
