Another theory regards a story in theEngishiki.Nietono was a kitchen in the imperial court where tributes such as fish were presented from various provinces, including Tosa. The name was later changed fromNietonogawa toNiyodogawa.[3]
Yet another theory states that since ancient times, the Niyodo River was called "Miwagawa" (三輪川, lit.Divine River) because sake to be offered to the great gods was brewed in this river, and it is said that it eventually became Niyodogawa.[3]
The Niyodo River rises from the confluence of the Omo and Kuma Rivers. The Omo River, which originates fromMount Ishizuchi, and the Kuma River, which flows from the Misaka Pass, join together in Mimido (Kumakōgen, Ehime) to form the Niyodo. The river then flows south, carving a deep valley in theShikoku Mountains, and eventually empties into the Pacific Ocean near the cities ofKōchi andTosa.National Route 33, which connectsMatsuyama and Kōchi, runs parallel to the section from Misaka Pass through Mimido toOchi.[4]
The river is known for its good water quality. In July 2012, it topped a central government-released national ranking of river water quality.[5]
The Niyodo River is visited by many tourists for the beauty of its clear blue color.[5][7] Tourist activities include camping, fishing,[8] biking,[9][10] and various festivals.[11] Popular sightseeing locations along the river include:
