 The line was extended to Nayoro in 1903, and to Wakkanai in 1922 along the route of the later Tempoku Line (, Tenpoku-sen) via Hamatombetsu.The present route via was opened as part of the Teshio Line (, Teshio-sen).After Japan's defeat in the war, the line lost its function as a link to Sakhalin, but remained important as a trunk line into the northern part of Hokkaido.