On December 10, 1934, the Japanese Government Railways (JGR) opened the Aniai Line (阿仁合線) connecting Takanosu with Yonaizawa over a length of 15.1 kilometers.

[1] Following World War II, the JGR became the Japanese National Railways (JNR), and the line was further extended to Hitachinai by October 15, 1963.

[1] On November 1, 1971, the JNR Kakunodate Line began operations from Kakunodate to Matsuba,[1] with construction continuing north towards Hitachinai to provide a connection to the Aniai Line.

However construction was suspended in 1980 due to JNR funding constraints.

[1] It also recommenced construction of the suspended link (known as the New Line) which opened on April 1, 1989 creating the current through-route.