Ōmura Line

The railway was built by the private Kyushu Railway and opened in two stretches in 1898 as part of the company's original route toward Nagasaki. The first section, between Haiki and Ōmura, opened on 20 January 1898 under the name Nagasaki Line, and on 27 November the same year it was extended from Ōmura through Isahaya to Nagayo, carrying the main line on toward the city of Nagasaki by way of the present-day Ōmura corridor.

Like Japan's other major private railways of the era, the Kyushu Railway was taken into state ownership under the Railway Nationalization Act, becoming a government railway on 1 July 1907. When the government's nationwide line-naming regulations were issued, the route was incorporated into the Nagasaki Main Line on 12 October 1909, and for the next quarter-century the tracks along Ōmura Bay formed the principal rail approach to Nagasaki.

The line's identity changed when a more direct coastal route to Nagasaki was completed. With the opening of the Hizen-Yamaguchi (now Kōhoku) to Isahaya section of the Nagasaki Main Line on 1 December 1934, through traffic shifted to the new alignment, and the older Haiki–Isahaya tracks were separated off and renamed the Ōmura Line. Over the following decades several intermediate stations were added to serve communities along the bay, including Takematsu in 1922, Chiwata in 1928, Ogushigō in 1944 and Iwamatsu in 1945.

With the privatisation and break-up of Japanese National Railways on 1 April 1987, the Ōmura Line passed to the newly formed JR Kyushu, and freight operations on the line were discontinued. Suwa Station was added in 1989, and in the early 1990s the line gained a new role as the gateway to a major tourist development.

On 10 March 1992 Huis Ten Bosch Station opened to serve the new resort of the same name, and the 4.7 km section between Haiki and Huis Ten Bosch was electrified at 20 kV 60 Hz AC to allow through running of the electric "Huis Ten Bosch" limited express from the Hakata direction; the rest of the line remained non-electrified and worked by diesel railcars. In 2002 the line hosted an Imperial special train.

In more recent years JR Kyushu has modernised the line's operation: the IC fare card SUGOCA was introduced in 2012, the new YC1-series hybrid diesel-electric railcars entered service in 2020, and on 23 September 2022 two new stations — Shin-Ōmura and Ōmura-Sharyō-Kichi — opened, the former built as an interchange with the West Kyushu Shinkansen, which began running between Takeo-Onsen and Nagasaki that same day. Today the Ōmura Line carries local trains and the rapid "Seaside Liner" along Ōmura Bay, linking the Sasebo area with Isahaya and onward connections toward Nagasaki.

• 189820 January: the Kyushu Railway opens the Haiki–Ōmura section as the Nagasaki Line.
• 189827 November: the line is extended from Ōmura through Isahaya to Nagayo.
• 19071 July: the Kyushu Railway is nationalised under the Railway Nationalization Act and the line becomes a government railway.
• 190912 October: under the national line-naming regulations the route is incorporated into the Nagasaki Main Line.
• 192225 May: Takematsu Station opens.
• 192820 April: Chiwata Station opens.
• 19341 December: with the opening of the Hizen-Yamaguchi (now Kōhoku)–Isahaya section of the Nagasaki Main Line, the Haiki–Isahaya tracks are separated and renamed the Ōmura Line.
• 194421 October: Ogushigō Station opens.
• 194520 April: Iwamatsu Station opens.
• 19871 April: with the privatisation of Japanese National Railways the line passes to JR Kyushu; freight operations are discontinued.
• 198911 March: Suwa Station opens.
• 199210 March: Huis Ten Bosch Station opens and the 4.7 km Haiki–Huis Ten Bosch section is electrified at 20 kV 60 Hz AC for the 'Huis Ten Bosch' limited express.
• 2002An Imperial special train (Omeshi-ressha) runs on the line.
• 20121 December: the SUGOCA IC fare card is introduced on the line.
• 202014 March: the new YC1-series hybrid diesel-electric railcars enter service.
• 202223 September: Shin-Ōmura and Ōmura-Sharyō-Kichi stations open; Shin-Ōmura is an interchange with the West Kyushu Shinkansen, which opens the same day.