What is the main setting in the novel, Grenade?

Okinawa is the overall setting for the novel. It is a real country adjacent to Japan and became part of Japan years before the events of this novel. Before the Americans were set to land on Okinawa, the people were somewhat autonomous with their own religions, social structure, and dialect. However, the Japanese government set restrictions in play in advance of the Americans' arrival. There are specific settings in Okinawa that are important to the events of this novel, including the beach, the Shuri Castle, and the tomb of Hideki's ancestors. There are also general settings, including the caves and the countryside where the fighting takes place.