The railway was opened as a 762mm-railway from Hanamaki to Sennintoge (Sennin Pass), which is 3.9 km NE of present Ashigase station. The plan was to reach Kamaishi. However, the railway company couldn't afford to complete the railway due to the very steep gradient. The freight was instead taken by a cable way, the passengers had to walk down to Ōhashi. From there, it was a mining railway to Kamaishi.
After many troubles, due to war and tyhpoons, a new line was built another way over the mountain from Ashigase to Ōhashi and Kamaishi.