Ōu Mountains
 The Ōu Mountains (奥羽山脈 Ōu-sanmyaku) are a mountain range in the Tōhoku region of Honshū Japan. The range is the longest range in Japan and stretch 500 km (311 mi) south from the Natsudomari Peninsula of Aomori Prefecture to the Nasu volcanoes at the northern boundary of the Kantō region. Though long the range is only about 35 kilometres (22 mi) wide.