Kishin Line

The line was not built as a single project but assembled over thirteen years from several separate routes opened by the national railway's predecessor, the Railway Ministry. The earliest piece was the Sakubi Line (作備線), which opened on 21 August 1923 from Tsuyamaguchi through Tsuyama to Mimasaka-Oiwake, in the Okayama interior around Tsuyama. Over the following two years it was pushed northwest, reaching Kuse in 1924 and Chūgoku-Katsuyama in 1925, working its way up the valley toward Niimi.

A second front was opened from the Niimi end. On 14 April 1929 the Sakubi West Line (作備西線) opened between Niimi and Iwayama, and the original route was renamed the Sakubi East Line to distinguish the two. The gap between them was finally closed on 11 December 1930, when the Chūgoku-Katsuyama–Iwayama section opened and the reunited route through Tsuyama to Niimi took back the name Sakubi Line. A connecting stretch east of Tsuyama — the Tsuyama–Higashi-Tsuyama segment — had already been built in 1928 as part of the Inbi South Line (later the Inbi Line).

Meanwhile the line was also being built inland from Himeji. The Himetsu Line (姫津線) opened its first section, Himeji to Yobe, on 1 September 1930, and was extended in stages — to Higashi-Hashisaki in 1931, to Harima-Shingū in 1932, and to Mikazuki in March 1934. In November 1934 a separate Himetsu West Line (姫津西線) opened eastward from Higashi-Tsuyama to Mimasaka-Emi, and the original Himeji-side route was renamed the Himetsu East Line. The Himetsu East Line then reached Sayo in July 1935.

The last gap in the corridor — the stretch between Sayo and Mimasaka-Emi — was bridged on 8 April 1936, at which point the two Himetsu sections and the new link were unified once more as the Himetsu Line, giving a continuous railway from Himeji almost all the way to Niimi. The whole route took its modern identity on 10 October 1936, when the Sakubi Line and the Higashi-Tsuyama–Tsuyama portion of the Inbi Line were merged into the Himetsu Line and the through route from Himeji to Niimi was renamed the Kishin Line. A short branch from Tsuyama to Tsuyamaguchi was later separated from the line on 1 June 1944, when the nationalisation of the private Chūgoku Railway folded it into the Tsuyama Line.

In the post-war decades the Kishin Line settled into its role as a rural diesel route. Its first semi-express services, the 'Misasa' and 'Mimasaka', began on 1 October 1960 and were later upgraded to express status, while steam locomotives were withdrawn from the line on 25 March 1971. Centralised traffic control (CTC) was introduced in November 1986. On 1 April 1987 the line passed from the Japanese National Railways to the newly formed JR West under the privatisation of JNR, and freight operations over the whole line ended the same day.

The line's through limited-class trains did not survive the privatisation era for long: on 11 March 1989 the 'Misasa' and 'Mimasaka' expresses were abolished and replaced by rapid services between Himeji and Tsuyama, ending regular express running on the line. Investment in later years concentrated on the busier eastern end. New KiHa 122 and KiHa 127 series diesel railcars entered service between Himeji and Kōzuki on 14 March 2009, and a speed-up project completed on 13 March 2010 raised the maximum speed on the Himeji–Kōzuki section to 100 km/h. The ICOCA contactless fare card was introduced between Himeji and Harima-Shingū on 26 March 2016.

The line has been cut by serious flooding more than once in recent years. In August 2009 heavy rain from Typhoon No. 9 washed out an embankment and severed the central section, with full operation restored only on 5 October 2009 after about two months of substitute bus services. The torrential rains of July 2018 again closed the Tsuyama–Niimi and Kōzuki–Tsuyama sections; service was restored piecewise over the following weeks, with the final Chūgoku-Katsuyama–Niimi stretch reopening on 31 August 2018. Today the Kishin Line remains a lightly used but complete cross-country diesel link through the heart of the Chūgoku region.

• 192321 August: the Sakubi Line opens from Tsuyamaguchi through Tsuyama to Mimasaka-Oiwake — the first section of what becomes the Kishin Line.
• 1925The Sakubi Line is extended northwest from Tsuyama, reaching Kuse on 1 May 1924 and Chūgoku-Katsuyama on 15 March 1925.
• 192815 March: the Inbi South Line opens from Tsuyama through Higashi-Tsuyama to Mimasaka-Kamo, building the Tsuyama–Higashi-Tsuyama segment later absorbed into the Kishin Line.
• 192914 April: the Sakubi West Line opens between Niimi and Iwayama; the original route is renamed the Sakubi East Line.
• 19301 September: the Himetsu Line opens its first section, Himeji to Yobe. On 11 December the Chūgoku-Katsuyama–Iwayama gap is closed, reuniting the Tsuyama-side route to Niimi as the Sakubi Line.
• 1934The Himetsu Line is extended from Himeji in stages, reaching Mikazuki by 24 March; on 28 November the Himetsu West Line opens from Higashi-Tsuyama to Mimasaka-Emi and the Himeji-side route is renamed the Himetsu East Line.
• 193530 July: the Himetsu East Line is extended from Mikazuki to Sayo.
• 19368 April: the last gap, Sayo–Mimasaka-Emi, opens and the Himetsu sections are reunified as the Himetsu Line. On 10 October the Sakubi Line and the Higashi-Tsuyama–Tsuyama part of the Inbi Line are merged in and the Himeji–Niimi route is renamed the Kishin Line.
• 19441 June: with the nationalisation of the private Chūgoku Railway, the branch from Tsuyama to Tsuyamaguchi (1.9 km) is transferred to the Tsuyama Line.
• 19601 October: the first semi-express trains on the line, the 'Misasa' and 'Mimasaka', begin running (later upgraded to express).
• 197125 March: steam locomotive services are withdrawn from the Kishin Line.
• 19871 April: under the privatisation of Japanese National Railways, the line is transferred to JR West; freight operations over the whole line are abolished the same day.
• 198911 March: the 'Misasa' and 'Mimasaka' expresses are abolished and replaced by rapid services between Himeji and Tsuyama, ending regular express running on the line.
• 200914 March: new KiHa 122 and KiHa 127 series diesel railcars enter service between Himeji and Kōzuki. In August, Typhoon No. 9 floods sever the central section; full operation is restored on 5 October.
• 201613 March 2010: a speed-up project is completed, raising the maximum speed on the Himeji–Kōzuki section to 100 km/h; on 26 March 2016 the ICOCA contactless fare card is introduced between Himeji and Harima-Shingū.
• 2018July: heavy rain closes the Tsuyama–Niimi and Kōzuki–Tsuyama sections; service is restored in stages, with the final Chūgoku-Katsuyama–Niimi stretch reopening on 31 August.