a river in Japan, in the southeastern part of the island of Hokkaido. The Tokachi measures 196 km in length and drains an area of 8,780 sq km. The river originates on the eastern slopes of the Taisetsu-zan, flows across the Tokachi Plain, and empties into the Pacific Ocean. The portion that flows across the plain is navigable for vessels with a small water displacement. The cities of Obihiro, Makubetsu, and Ikeda are located on the Tokachi.