It rises from Mikamine in the Suō Mountains located on the border of Shimane Prefecture, flows further south through Lake Ohara (Sabagawa Dam), crosses the Chūgoku Expressway, turns to the southwest, crosses the northwestern part of Hōfu city, and then flows into the Suō Sea of the Seto Inland Sea.

Tōdai-ji dispatched the noted monk Chōgen in 1186 to raise funds and to procure the necessary timber and other raw materials from the mountains of Saba District in Suō.According to legend, when Chōgen overhear some of the workers complaining that they had not eaten any fish since they left Yamato, he wrote a magical pray on a piece of scrap wood, which turned into a mackerel ("saba") when he tossed it in the river.

All have been destroyed over time through neglect, flooding and typhoon damage, and only the ruins of the first and second weirs located at the Tukuji Funaji neighborhood of Yamaguchi City remain.

This weir raised the water level via a shallow dam, and had an opening with a width of approximately 5.4 meters to create a long and narrow waterway for timber flow, with flat stones on the bottom of the river to enable the logs to slide easier.

Chōgen constructed a number of these facilities in order to treat sicknesses and injuries of people engaged in work such as logging and transporting lumber.