The story
The Sendai–Yatsushiro section was built by the (then) Japanese Imperial Railway and opened between 1922 and 1927, at which time this route replaced the Hisatsu Line to become the southern part of the Kagoshima Main Line.
The Yunoura–Tsunagi section was duplicated between 1966 and 1968. CTC signalling was commissioned from Yatsushiro–Sendai in 1969/70, and the line was electrified in 1970.
In 2004, following the opening of the Kagoshima–Shin Yatsushiro section of the Kyushu Shinkansen, operation of the section was transferred under the Third Sector arrangements.
Former connecting lines
Minamata Station: The first section of the Yamano line was opened from Kurino (on the Hisatsu Line) 24 km to Yamano in 1921. The 14 km Minamata–Kugino section opened in 1934, and the 10 km Yamato–Satsuma section the following year. In 1937 the 8 km Kugino–Satsuma section, including the Okawa spiral opened. Freight services ceased in 1986, and the line closed in 1988.
From Wikipedia’s article on Hisatsu Orange Railway, shared under CC BY-SA 4.0.4