The Japanese government categorizes it as a Class 1 river. With a length of , the Naka drains an area of , including parts of neighboring Fukushima Prefecture. Its source is at Nasu-dake in Nikkō National Park.
The Naka River, classified as a Class 1 river by the Japanese government, has a length of and drains an area of , encompassing portions of neighboring Fukushima Prefecture. It originates from Nasu-dake within Nikkō National Park.