Chōkai Sanroku Line

The corridor began as a private venture. On 1 August 1922 the Yokoshō Railway (横荘鉄道) opened its "West Line" between Ugo-Honjō and Maegō, a distance of 11.6 km. The Yokoshō Railway's wider ambition had been to build clear across the region between Yokote and Honjō, but its line was completed only in sections at either end and the two halves were never joined.

On 1 September 1937 the state purchased and nationalised the Yokoshō Railway's West Line, and the Japanese Government Railways renamed the Ugo-Honjō–Maegō section the Yashima Line (矢島線). Under state ownership the line was then pushed deeper into the hills: it was extended from Maegō to Nishitakisawa on 15 December 1937, and on 21 October 1938 a further 7.3 km opened from Nishitakisawa to Ugo-Yashima, bringing the railhead to what is today the terminus and giving the line its full 23.0-kilometre length.

For the next several decades the Yashima Line settled into the role of a quiet rural branch. Steam haulage gave way to diesel railcars on 20 April 1961, and freight working, long in decline, was discontinued on 10 March 1981.

The line's future was thrown into doubt by the national railway's financial crisis. Under the 1980 law to restructure the deficit-ridden Japanese National Railways, lightly used rural lines were designated "specified local lines" (特定地方交通線) for closure or conversion, and the Yashima Line was named in the first batch of such lines on 11 September 1981. Rather than abandon it, local interests established a third-sector company, the Yuri Kōgen Railway, to take the line over.

The handover took place on 1 October 1985: Japanese National Railways discontinued the Yashima Line as a national railway, and the Yuri Kōgen Railway began operating the same 23.0-kilometre route as the Chōkai Sanroku Line. The new company gradually built up the line's local service — on 29 October 1989 two new stations, Magosawa and Yoshisawa, were opened to serve communities along the route.

As a small rural railway dependent on tourism as well as commuters, the line has leaned on its scenery and local colour. One morning round trip is run as the "Magokoro-ressha" (まごころ列車), staffed by an attendant dressed as an Akita "obako" country girl. From 2012 to 2014 the company introduced three new YR-3000 series diesel railcars to replace its ageing fleet; each of the three cars is finished mainly in white but accented in a different colour — green, red and blue — with interiors decorated to match, presenting the line and its Mount Chōkai backdrop to visitors riding up the valley.

• 19221 August: the Yokoshō Railway opens its West Line between Ugo-Honjō and Maegō (11.6 km).
• 19371 September: the state purchases and nationalises the Yokoshō Railway's West Line, renaming the Ugo-Honjō–Maegō section the Yashima Line.
• 193715 December: the Yashima Line is extended from Maegō to Nishitakisawa (4.1 km).
• 193821 October: the line is extended from Nishitakisawa to Ugo-Yashima (7.3 km), reaching the present terminus and its full 23.0 km length.
• 196120 April: diesel railcars replace steam locomotives on the line.
• 198110 March: freight service on the Yashima Line is discontinued.
• 198111 September: the Yashima Line is designated in the first batch of 'specified local lines' to be closed or converted under the law restructuring Japanese National Railways.
• 19851 October: Japanese National Railways discontinues the Yashima Line (Ugo-Honjō–Ugo-Yashima, 23.0 km); it is converted to the third sector and reopens as the Yuri Kōgen Railway's Chōkai Sanroku Line.
• 198929 October: two new stations, Magosawa and Yoshisawa, are opened along the line.
• 2012From 2012 to 2014 the Yuri Kōgen Railway introduces three YR-3000 series diesel railcars — finished mainly in white with green, red and blue accents respectively — to replace its ageing fleet.