Ojiri River

Japanese: 大尻川 - おおじりがわ

...A waterfall in Nikko City, western Tochigi Prefecture. The Ojiri River (the source of the Daiya River) originating from Lake Chuzenji falls over lava erupted from Mt. Nantai, forming a waterfall about 97m high and 7m wide. The deepest part of Lake Chuzenji is 163m below the surface, while Kegon Falls is only 97m deep. It is believed that the old Oya River before the formation of Lake Chuzenji was slightly closer to Mt. Nantai than the current location of Kegon Falls.

From [Otani River]

…The main river has a length of 30 km and a total drainage area of 259 km2. The river is commonly called the Ojiri River until it becomes Kegon Falls and flows down. The Kegon Valley from Umagaeshi in the upper reaches to Kegon Falls is a deep valley, part of which was formed by the retreat of Kegon Falls. …

*Some of the terminology that refers to the Ojiri River is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…栃木県西部，日光市にある滝。中禅寺湖から発した大尻（おおじり）川(大谷（だいや）川源流部)が男体山から噴出した溶岩にかかって，高さ約97m，幅約7mの滝となっている。中禅寺湖の最深部は水面下163mあるのに対し，華厳滝は97mしかなく，中禅寺湖形成以前の古い大谷川は，現在の華厳滝の位置よりは若干男体山側に寄っていたと考えられる。…