The story takes place on Hajima, a tiny island in Nagasaki Prefecture that once served as the base for an undersea coal mine, until those operations closed in 1974. While the island is now deserted, this tale spans a half-year period from spring to autumn of 1959, when the mine was in full swing and the island’s resident population reached a record high of 5,100. Given Hajima’s scant size at .063 square kilometers (15.5 acres), its population density in the novel’s timeframe is greater than that of Tokyo. Even today the island is known by its “battleship island” nickname Gunkanjima, because of the many tall concrete buildings that make its landmass resemble a warship.
