Inbi Line

The line began as a light railway built by the Japanese Government Railways. Its first section, from Tottori to Mochigase, opened on 20 December 1919 as the Inbi Light Railway (因美軽便線). On 2 September 1922 it was reclassified and renamed the Inbi Line, and on 5 June 1923 it was extended south from Mochigase to Chizu, reaching deeper into the hills.

Construction of the southern half proceeded separately from the Tsuyama end. On 15 March 1928 the Inbi South Line (因美南線) opened from Tsuyama to Mimasaka-Kamo; at the same time the original northern portion was redesignated the Inbi North Line (因美北線). The South Line was pushed on from Mimasaka-Kamo to Mimasaka-Kawai on 12 September 1931.

The two halves were joined on 1 July 1932, when the final gap was closed — a stretch that included a tunnel of 3,077 metres — and the through route was once again unified under the single name Inbi Line. A few years later, on 10 October 1936, the short Higashi-Tsuyama to Tsuyama segment was transferred to the Kishin Line, fixing the Inbi Line's southern terminus at Higashi-Tsuyama, where it remains today.

Like most rural lines, the Inbi Line was steadily modernised after the war. It was fully converted to diesel railcar operation on 1 July 1982. With the breakup and privatisation of the Japanese National Railways on 1 April 1987, the line passed to the newly formed JR West. One-man operation was introduced on 1 April 1991, the same day the Tottori Railway Operations Department was established to manage the route, and centralised traffic control (CTC) was commissioned on 1 March 1994.

The line's role in long-distance travel changed sharply at the end of 1994. On 3 December 1994 the third-sector Chizu Express opened its Chizu Line, branching off at Chizu, and the limited express "Super Hakuto" began running between the Kansai region and the San'in coast over that faster route rather than the full length of the Inbi Line. The older through express "Sakyū" was discontinued on 29 November 1997. The line was given a speed-up on 1 October 2003.

Today the Inbi Line is worked mainly by local diesel services, with the Tottori–Chizu section also carrying the "Super Inaba" limited express linking Tottori and Okayama via the Chizu Express. Operation of the route is divided, with the Tottori end and the Okayama end managed by different JR West organisations and Chizu treated as a boundary station. The line has on occasion been closed by natural disasters: the heavy rain of early July 2018 suspended the whole line on 5 July 2018, with services restored in stages until full operation resumed on 31 August 2018.

• 191920 December: the Inbi Light Railway (因美軽便線) opens its first section, Tottori–Mochigase.
• 19222 September: the line is reclassified and renamed the Inbi Line.
• 19235 June: the line is extended south from Mochigase to Chizu.
• 192815 March: the Inbi South Line (因美南線) opens from Tsuyama to Mimasaka-Kamo; the original northern portion is redesignated the Inbi North Line (因美北線).
• 193112 September: the Inbi South Line is extended from Mimasaka-Kamo to Mimasaka-Kawai.
• 19321 July: the remaining gap (including a 3,077 m tunnel) is closed, completing the line; it is reunified as the Inbi Line.
• 193610 October: the Higashi-Tsuyama–Tsuyama section is transferred to the Kishin Line, fixing the southern terminus at Higashi-Tsuyama.
• 19821 July: the line is fully converted to diesel railcar operation.
• 19871 April: with the breakup and privatisation of the Japanese National Railways, the line passes to JR West.
• 19911 April: one-man operation begins and the Tottori Railway Operations Department is established.
• 19941 March: centralised traffic control (CTC) is commissioned (EN: between Tottori and Chizu).
• 19943 December: the third-sector Chizu Express opens, branching off at Chizu; the limited express 'Super Hakuto' begins running over the new route.
• 199729 November: the through express 'Sakyū' (砂丘) is discontinued.
• 20031 October: the line undergoes a speed-up.
• 20185 July: the whole line is suspended by the early-July 2018 heavy rain; full operation resumes on 31 August after staged restoration.