Maniwa (真庭市, Maniwa-shi) is a city located in north-central Okayama Prefecture, Japan. Its northernmost border meets that of Tottori Prefecture. The modern city of Maniwa was established on 31 March 2005, from the merger of the town of Hokubō (from Jōbō District); the towns of Katsuyama, Ochiai, Yubara and Kuse, and the villages of Mikamo, Kawakami, Yatsuka and Chūka (all from Maniwa District), the latter three which make up the area of Hiruzen as a whole. As of 1 April 2018, Maniwa has an area of 828.43 km², 11.6% of Okayama Prefecture, giving it the largest area of any municipality in the prefecture. It measures roughly 55km from North to South, and 35km from East to West. Its population was 44,265, with 17,828 households. The city is known for Mount Hiruzen (1,202 m) and the Hiruzen Highlands. Mount Hiruzen (also known as the Hiruzen Sanza, for its 3 sloping peaks) is also the source of the Asahi River (142 kilometres), which flows through much of Okayama Prefecture. Maniwa is also currently known for its Biomass initiatives and has been given the title of a "Biomass Town", alongside 317 other areas within Japan. It has a biomass power plant, which runs using woody biomass in the forms of by-products of the city's lumber industries and household waste. The plant products over 10,000kW of energy, and can fuel more than 22,000 of Maniwa's homes, of which it sells some of the energy back to the National Grid. The City Office in Kuse is also fueled by a biomass boiler, and also uses solar panels in an attempt to reduce its carbon footprint.