Shinminato-kō Line

The section that is now the Shinminato-kō Line was not built by the company that built the Takaoka end. It was constructed by Etchū Railway, which opened the first stretch — Nishi-Koshinogata (no longer extant) to Shinminato-Higashiguchi (today's Higashi-Shinminato) — on 12 October 1930, followed by the short Koshinogata–Nishi-Koshinogata segment on 23 December 1930. The line was extended westward in stages: to Shōgawaguchi in November 1932 and on to Shin-Fushikiguchi (today's Rokudōji) in December 1933, knitting together the coastal towns east of the Shōgawa river.

In 1943 Etchū Railway was absorbed by Toyama Chihō Railway, and the route became that company's Imizu Line. A major change came on 1 April 1951, when a 3.6-kilometre segment from Yonejimaguchi to Shinminato (today's Rokudōji) opened — taking over passenger duty from the discontinued national-railway Shinminato Line — and through running began across the Imizu Line linking the Takaoka tramway with the Toyama city tram network. The Yonejimaguchi–Shinminato segment was transferred to Kaetsunō Railway in 1959.

The line's modern identity was forged by the construction of Toyama Shinkō (the new industrial port). In 1966 the harbour works severed the Imizu Line, cutting off the through route to Toyama; the surviving Shinminato-to-Koshinogata stub was transferred from Toyama Chihō Railway to Kaetsunō Railway on 5 April 1966 and renamed the Shinminato-kō Line. With the Toyama connection gone and motorisation rising, ridership entered a long decline, and the line converted to one-man operation in November 1971, leaving its intermediate stations unstaffed.

The line came close to disappearing in the 1970s. On 11 September 1976 a typhoon washed away the Shōgawa river bridge, cutting the Shinminato–Koshinogata section; the segment was on the verge of abandonment, but a residents' preservation campaign saved it, and through service was restored on 1 October 1977. In December 1980 the combined Takaoka Kidō and Shinminato-kō lines were given the public nickname "Manyosen," the name by which the system has been known ever since.

By the turn of the century the operator, Kaetsunō Railway, wished to abandon both the Takaoka Kidō and Shinminato-kō lines. To keep them running, the city of Takaoka and the former city of Shinminato led the creation of a third-sector company, Manyosen Co., Ltd., established on 5 April 2001; the transfer was approved on 14 February 2002, and operations began under the new company on 1 April 2002. Several stations were renamed over the following decades — Shinminato became Rokudōji in 1985, and the Koshinogata-end Kaiōmaru station took its present name in 1990 — and IC fare cards (ICOCA) became usable on the line from 28 September 2024.

• 193012 October: Etchū Railway opens the first segment of what is now the Shinminato-kō Line, Nishi-Koshinogata (no longer extant)–Shinminato-Higashiguchi (now Higashi-Shinminato), 1.2 km; the Koshinogata–Nishi-Koshinogata segment (0.2 km) follows on 23 December.
• 19329 November: the line is extended from Shinminato-Higashiguchi to Shōgawaguchi (2.7 km).
• 193325 December: the line is extended from Shōgawaguchi to Shin-Fushikiguchi (today's Rokudōji), 0.6 km.
• 19431 January: Etchū Railway is absorbed by Toyama Chihō Railway; the route becomes that company's Imizu Line.
• 19511 April: the Yonejimaguchi–Shinminato (now Rokudōji) segment, 3.6 km, opens — taking over passenger service from the discontinued national-railway Shinminato Line — and through running begins across the Imizu Line to the Toyama city tram network.
• 19591 April: the Yonejimaguchi–Shinminato segment is transferred from Toyama Chihō Railway to Kaetsunō Railway.
• 19665 April: with the Imizu Line severed by the construction of Toyama Shinkō, the surviving Shinminato–Koshinogata segment is transferred from Toyama Chihō Railway to Kaetsunō Railway and named the Shinminato-kō Line.
• 197115 November: the line converts to one-man operation, and the Shinminato-kō Line's intermediate stations are fully destaffed.
• 197611 September: a typhoon washes out the Shōgawa river bridge, suspending the Shinminato–Koshinogata section; it is nearly abandoned but saved by a residents' preservation campaign.
• 19771 October: the Shinminato–Koshinogata section is restored to service.
• 19806 December: the combined Takaoka Kidō and Shinminato-kō lines are given the public nickname "Manyosen".
• 1985March: Shinminato Station is renamed Rokudōji Station (and Nishi-Shinminato, 1st, becomes Shinminato City Hall-mae).
• 20021 April: after Kaetsunō Railway sought to abandon the line, operations begin under the new third-sector Manyosen Co., Ltd. (established 5 April 2001; transfer approved 14 February 2002).
• 202428 September: IC fare cards (ICOCA) become usable on the line.