The is a Japanese railway line connecting Kiryà « Station in Kiryà «, Gunma and Matà  Station in Nikkà Â, Tochigi. This is the only railway line that the third-sector company operates. The company and line are also known as or . The company acquired the line from the East Japan Railway Company (JR East) in 1989. As the name suggests, the line runs along the Watarase River through a deep valley.
The Ashio Railway Co. opened the line to Ashio-Motoyama ( beyond Mato) in 1911âÂÂ12 to service the Ashio Copper Mine, and leased the line to JNR in 1913. Passenger services were introduced in 1914. In 1918 the line was nationalised.
The copper mine closed in 1973, the same year the line was deviated for the construction of the Kusaki Dam, including the Kusaki Tunnel.
Operation of the line between Kiryà « and Matà  was transferred to the Watarase Keikoku Railway, a third-sector company, in 1989. Also in 1989, the Ashio-MotoyamaMato section was closed.