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island, western Niigata ken (prefecture), central Japan, in the Sea of Japan (East Sea), 32 miles (51 km) west of Honshu. It faces Niigata, the prefectural capital, across the Sado Strait. With an area of 331 square miles (857 square km), it is the fifth largest Japanese island. Sado is crowned by two parallel mountain chains; its topography includes dramatic precipices and ravines, mountain streams, and Lake Kamo