Kotoden Nagao Line

The line was built not by the state railway but by the Takamatsu Electric Tramway (Takamatsu Denki Kidō), one of the three predecessor companies of today's Kotoden. The company received its tramway charter on 30 May 1907, for a route between Shinminato-chō in Takamatsu and the village of Nagao in Ōkawa District, and was formally established on 28 October 1909.

The first and main section opened on 30 April 1912, running between Dehare — a station near the present Kawaramachi, by what is now the Shido Line side of that station — and Nagao. It was built as a tramway to 1,067 mm narrow gauge and electrified at 600 V DC. A licence to extend the line beyond Nagao toward Shirotori-honchō was obtained later in 1912 but lapsed in 1916, and the route was never built; the line has remained a Kawaramachi–Nagao service ever since. Through the 1910s and 1930s a number of small intermediate stations were opened, renamed and closed as traffic settled.

The wartime years brought the line under the Kotoden name and reshaped its physical character. On 1 November 1943 three local companies — the Sanuki Electric Railway, the Kotohira Electric Railway and the Takamatsu Electric Tramway — merged to form the Takamatsu-Kotohira Electric Railroad, bringing the Nagao Line into the Kotoden group it still belongs to. On 1 February 1945 the line was reclassified from a tramway under the Tramway Act to a railway under the Local Railway Act. Then, over June 1945, it was regauged from 1,067 mm to the 1,435 mm standard gauge used by Kotoden's other lines: the Dehare–Takada section on 2 June and the Takada–Nagao section on 26 June. With the regauging complete, through-running onto Kotoden's city (Kotohira-side) tracks began.

The end of the war damaged the line's inner end. In July 1945 air raids burned out Dehare Station, which was abolished; its functions were consolidated into Kawaramachi, which thereby became the line's terminus. Through-running onto the city line was suspended because of the war damage, and freight operations were halted around the same time. In the post-war decades the line settled into a local-transport role, with further small changes to its intermediate stations, including the opening of Shinkōji Station (later renamed Ido) in 1947 and a reconfiguration of the Kawaramachi-side approach in the early 1950s.

Modernisation came gradually in the second half of the twentieth century. On 26 December 1976 the overhead voltage of the whole line was raised from 600 V to 1,500 V, matching the rest of the Kotoden network. Automatic train stop (ATS) was installed on 20 November 1977. In November 1978 a collision between a train and a dump truck at the Kashifuse-Chūō level crossing killed two people, one of several reminders of the safety challenge posed by the line's many crossings.

In recent decades the Nagao Line has been integrated more closely into Kotoden's network and has gained new suburban stations on the Takamatsu side. Through-running to Takamatsu-Chikkō, beside the harbour, began on 26 June 1994, giving Nagao Line trains a direct run into the heart of Takamatsu. Gakuen-dōri Station opened on 28 September 2002, and larger 18-metre 1200-series cars entered service from 3 July 2006. On 18 March 2023 all-day one-man operation began on the Kawaramachi–Nagao section. Today the line carries standard-gauge electric multiple units — many of them former big-city commuter cars — linking central Takamatsu with its eastern suburbs and the pilgrimage town of Nagao.

• 190730 May: a tramway charter is granted to the Takamatsu Electric Tramway for a route between Shinminato-chō in Takamatsu and the village of Nagao in Ōkawa District.
• 190928 October: the Takamatsu Electric Tramway is established.
• 191230 April: the Dehare (near present Kawaramachi)–Nagao section opens as a tramway, built to 1,067 mm gauge and electrified at 600 V DC.
• 191624 April: the licence for a Nagao–Shirotori-honchō extension (obtained in 1912) lapses; the extension is never built.
• 19431 November: the Sanuki Electric Railway, the Kotohira Electric Railway and the Takamatsu Electric Tramway merge to form the Takamatsu-Kotohira Electric Railroad (Kotoden).
• 19451 February: the line is reclassified from a tramway under the Tramway Act to a railway under the Local Railway Act.
• 19452 June and 26 June: the line is regauged from 1,067 mm to 1,435 mm standard gauge — Dehare–Takada on 2 June and Takada–Nagao on 26 June; through-running onto Kotoden's city (Kotohira-side) tracks then begins.
• 194530 July: Dehare Station, burned out in air raids, is abolished and its functions consolidated into Kawaramachi, which becomes the line's terminus; through-running to the city line is suspended and freight operations are halted.
• 197626 December: the overhead voltage of the whole line is raised from 600 V to 1,500 V, matching the rest of the Kotoden network.
• 197720 November: automatic train stop (ATS) is installed.
• 19783 November: a train collides with a dump truck at the Kashifuse-Chūō level crossing, killing two people.
• 199426 June: through-running to Takamatsu-Chikkō, beside the harbour, begins.
• 200228 September: Gakuen-dōri Station opens.
• 20063 July: larger 18-metre 1200-series cars enter service.
• 202318 March: all-day one-man operation begins on the Kawaramachi–Nagao section.