Aogashima's roughly 160 residents live on the outer rim of an active volcano and climb down into its crater to work. The island lies about 358 kilometres south of Tokyo in the Philippine Sea, legally part of the capital and in practice the loneliest inhabited point of the Izu chain. Its outer caldera, Ikenosawa, is some 1.5 kilometres wide, and standing inside it is Maruyama, a 223-metre cone thrown up by the eruption of 1781-85. That eruption gave the island the shape it has today and nearly ended it: of 327 islanders, around 130 could not be evacuated in time and died, and the survivors left Aogashima empty for about fifty years. Japan's weather agency still lists the volcano as active.
The two hamlets cling to the northern rim, every house set above the sea. Climb Otonbu, the 423-metre high point, and the whole double crater opens below you: the green bowl, Maruyama's ridged cone at its centre, small terraced fields, and ocean to every horizon. The heat that made all of it is still just under the grass. On the crater floor at Ikenosawa the islanders tap steam vents they call hingya to cook eggs and vegetables in free public steamers, to heat a sauna and to turn seawater into salt. The island has no harbour, so the fishing boats are lifted in and out of the water by crane. Reaching Aogashima at all depends on the sea, and the ferry from Hachijojima sails only about half the days it is scheduled. After dark almost nothing is lit, and the Milky Way stands over the crater.