Seibu Yamaguchi Line

The line traces its origin to an amusement-park attraction. In 1950 Seibu opened the "Otogi Line" (おとぎ線), a single-track 762 mm narrow-gauge light railway whose battery-locomotive-hauled "Fantasy Train" (おとぎ電車 / おとぎ列車) carried sightseers through the recreation area Seibu had developed. The first section, from Tamako Hotel-mae to Kamientei, opened on 1 August 1950, and the following year, on 16 September 1951, the line was extended on to Unesco-mura, with Kamientei downgraded to the Yamaguchi signal post.

On 15 July 1952 the 3.7-kilometre Otogi Line, from Tamako Hotel-mae to Unesco-mura, was reclassified from an amusement ride into a local railway under the Local Railway Act and renamed the Yamaguchi Line, giving it the formal name Seibu Yamaguchi Line; the old "Fantasy Train" names nonetheless remained in use. Fares were charged separately from Seibu's other lines, and at first only battery-locomotive-hauled trains ran. Tamako Hotel-mae was renamed Seibu-Yūenchi in 1963 and again to Yūenchi-mae in 1979.

To mark the centenary of railways in Japan, steam-locomotive operation began on 2 June 1972, and from then on steam trains ran on the line outside the winter months, hauling wooden open-deck coaches acquired from the Ikasa Railway. The original German-built Koppel locomotives were borrowed and ageing, and their larger replacements needed track upgrading, so operation was suspended on 17 December 1976 and resumed on 19 March 1977; once the trackbed had been strengthened and tunnels opened out, double-headed steam trains also began to run.

The ageing facilities and rolling stock, together with a desire to improve access from the Tamako Line to the Seibu Lions' baseball stadium (today's Belluna Dome), prompted a wholesale rebuilding. The Ministry of Transport authorised the conversion to a new-transit system on 16 April 1984; the "Fantasy Train" made its farewell runs at a ceremony on 13 May, and the line closed for reconstruction on 14 May. Procedurally the old light railway was formally abolished and a fresh AGT licence obtained, and the route was partly realigned with new terminals.

On 25 April 1985 the line reopened in its present form as a rubber-tyred AGT railway running 2.8 kilometres from Seibu-Yūenchi to Seibukyūjō-mae, and the surviving Yūenchi-mae–Unesco-mura section was abolished the same day; fares were merged into Seibu's ordinary system. The engineers deliberately kept costs down: rather than driverless cab-signal/ATO automation the line was built with conventional lineside signals and ATS for one-person operation, and it adopted 750 V DC electrification with an eye to commercialising VVVF inverter control. The three four-car Series 8500 trainsets built for the opening were Seibu's first VVVF-inverter cars.

The Yamaguchi Line occupies an unusual niche among Japan's automated guideway systems. As of 2019 it was one of only two AGT lines in the country run by a purely private company—the other being the Yamaman Yūkarigaoka Line—and it remains the only guideway line in Japan that crosses a prefectural boundary, threading from Tokyo into Saitama. For most of its length it follows the northern shore of the Lower Murayama Reservoir (Lake Tama), though a protective watershed forest screens the lake from view for much of the ride.

On 13 March 2021 two of its stations were renamed—Seibu-Yūenchi became Tamako and Yūenchi-nishi became Seibuen-yūenchi—and from 1 April 2021 Seibu began running the Leo Liner on electricity from the Seibu Takeyama Solar Power Station, making it effectively carbon-neutral. On 27 March 2026 the new Series L00, built by Mitsubishi Heavy Industries as the first new trains in some forty years, entered service to replace the Series 8500; three four-car sets are planned by fiscal 2027.

3 stations tracked on the map, listed alphabetically. Select any to read its page.

• Seibuen-yuenchi西武園ゆうえんち
• Seibukyujo-mae西武球場前
• Tamako多摩湖

• 19501 August: Seibu opens the 762 mm narrow-gauge "Otogi Line" light railway, Tamako Hotel-mae–Kamientei, as a battery-locomotive-hauled amusement ride.
• 195116 September: the Otogi Line is extended Kamientei–Unesco-mura; Kamientei is downgraded to the Yamaguchi signal post.
• 195215 July: the 3.7 km Tamako Hotel-mae–Unesco-mura line is reclassified as a local railway under the Local Railway Act and renamed the Yamaguchi Line.
• 19631 July: Tamako Hotel-mae Station is renamed Seibu-Yūenchi.
• 19722 June: steam-locomotive operation begins, marking the centenary of railways in Japan.
• 197617 December: operations are suspended for track-renovation work.
• 197719 March: operations resume after the trackbed is strengthened.
• 197925 March: Seibu-Yūenchi Station is renamed Yūenchi-mae.
• 198416 April: the Ministry of Transport authorises conversion to a new-transit system; after the "Fantasy Train" makes its farewell runs on 13 May, the line closes for reconstruction on 14 May.
• 198525 April: the line reopens as a rubber-tyred AGT railway, Seibu-Yūenchi–Seibukyūjō-mae (2.8 km); the Yūenchi-mae–Unesco-mura section is abolished the same day. Three Series 8500 sets, Seibu's first VVVF-inverter cars, enter service.
• 202113 March: two stations are renamed (Seibu-Yūenchi → Tamako; Yūenchi-nishi → Seibuen-yūenchi); from 1 April the Leo Liner runs on power from the Seibu Takeyama Solar Power Station, effectively carbon-neutral.
• 202627 March: the Mitsubishi-built Series L00—the first new trains in some forty years—enters service, replacing the Series 8500.