Nishitetsu Kaizuka Line

The line began as a project of the Hakata Bay Railway and Steamship Company (博多湾鉄道汽船), which on 23 May 1924 opened the first section between Shin-Hakata — the station later renamed Chidoribashi — and Wajiro. The 1,067 mm gauge adopted on today's Kaizuka Line dates from this original Hakata Bay Railway construction. The following year, on 1 July 1925, the railway was extended from Wajiro to Miyajidake, the shrine town that would later give the longer line its name.

On 16 August 1929 the whole line was electrified at 1,500 volts, putting it on the same electrical standard it still uses today. During the wartime consolidation of Japan's private railways the company was absorbed by larger operators: on 19 September 1942 it was merged into the Kyushu Electric Railway (九州電気軌道), and just three days later, on 22 September 1942, that enlarged enterprise was renamed Nishi-Nippon Railroad, with the route becoming the company's Miyajidake Line.

Under Nishitetsu the line was extended once more. On 1 July 1951 a section from Miyajidake on to Tsuyazaki opened, pushing the railway further up the coast northeast of Fukuoka. The line was not without tragedy: on 8 July 1953 a head-on collision between Shingū and Mitoma killed four people. The route at this stage was a long coastal interurban running from the Hakata waterfront out to Tsuyazaki.

In 1954 the line's southern end was reconfigured in a way that would eventually split it from the rest. On 5 March 1954 the section between Nishitetsu-Hakata and Nishitetsu-Tatara was re-gauged to 1,435 mm standard gauge, had its voltage cut to 600 V, and was folded into the Fukuoka city tram network; that tramway section, including the stretch on to Kaizuka, was later closed in 1979. The northern Kaizuka–Tsuyazaki portion, meanwhile, remained 1,067 mm gauge and continued as the Miyajidake Line.

The opening of urban rapid transit then reshaped the line's southern access. On 12 November 1986 the Fukuoka City Subway's Hakozaki Line was extended to Kaizuka, and the Miyajidake Line's own track south of Kaizuka was given up, leaving Kaizuka as the line's terminus and an interchange with the subway. From this point passengers bound for central Fukuoka changed at Kaizuka onto the subway rather than riding through on Nishitetsu metals.

The decisive change came in 2007. On 1 April 2007, with ridership in long-term decline, Nishitetsu closed the 9.9-kilometre section between Nishitetsu-Shingū and Tsuyazaki and renamed the truncated remainder the Kaizuka Line. Since then the line has run only between Kaizuka and Nishitetsu-Shingū, a short two-car commuter operation feeding the Fukuoka City Subway at Kaizuka, and it remains in this role today as the last surviving fragment of the old Miyajidake Line.

• 192423 May: the Hakata Bay Railway and Steamship Company opens the first section, Shin-Hakata (later Chidoribashi)–Wajiro.
• 19251 July: the line is extended from Wajiro to Miyajidake.
• 192916 August: the whole line is electrified at 1,500 V.
• 194219 September: the company is merged into the Kyushu Electric Railway; on 22 September the enlarged firm is renamed Nishi-Nippon Railroad and the route becomes its Miyajidake Line.
• 19511 July: the Miyajidake–Tsuyazaki section opens, extending the line further up the coast.
• 19538 July: a head-on collision between Shingū and Mitoma kills four people.
• 19545 March: the Nishitetsu-Hakata–Nishitetsu-Tatara section is re-gauged to 1,435 mm standard gauge, reduced to 600 V, and incorporated into the Fukuoka city tram network.
• 19621 November: Kyōrinkiba-mae Station is renamed Kaizuka.
• 197911 February: the Chidoribashi–Kaizuka section is closed together with the Fukuoka city tram network.
• 19801 September: one-man (driver-only) operation begins on the line.
• 198612 November: the Fukuoka City Subway Hakozaki Line is extended to Kaizuka; the Miyajidake Line's track south of Kaizuka is given up and Kaizuka becomes the terminus and subway interchange.
• 20071 April: with ridership declining, the 9.9 km Nishitetsu-Shingū–Tsuyazaki section is closed and the remaining line is renamed the Kaizuka Line.
• 201013 March: the IC card 'nimoca' is introduced on the line.