It merges, at Mitaniguchi, a river originating in Mitani-toge Pass in the northern part of Ohara (Kyoto Prefecture), Sakyo Ward, and at Kodeishi-cho, the Takatani-gawa River which originates in Mt. Tenga-dake located at a boundary between Kurama, Sakyo Ward and Ohara, Sakyo Ward.
左京区大原(京都)北部のミタニ峠を源とする川を三谷口で合わせ、左京区鞍馬と左京区大原の境に位置する天ヶ岳を源とする高谷川を小出石町で合わせる。