Seibuen Line

The line traces its origin to an unbuilt scheme. The old Seibu Railway had obtained a licence in 1915 for a "Hakonegasaki Line" (formally the Murayama Line), an extension from Higashi-Murayama toward Hakonegasaki, but it repeatedly deferred construction and carried the dormant concession into the Shōwa era. The plan was revived after Murayama Reservoir — Lake Tama — was completed in 1927 and began drawing day-trippers from Tokyo as a nearby scenic spot. Rivals moved first: the Musashino Railway built a line toward the lake, while Hakone Tochi (later Kokudo) built a route from Kokubunji and handed it to its subsidiary, the Tamako Railway, today the Tamako Line.

A bitter competitor of the Musashino Railway, the old Seibu Railway adjusted its plan in 1929 to exploit the fact that the Hakonegasaki route would pass close to the reservoir, and built just a single stretch of line up to its edge. On 5 April 1930 the section from Higashi-Murayama to a provisional Murayama-Teisuiike-mae Station opened, 2.8 kilometres long, as part of the Murayama Line. The route was deliberately laid to confront the Tamako Railway. Shortly afterward, in 1931, the parent Hakonegasaki Line concession was revoked by the Railway Ministry, exasperated by the endless delays, leaving the company to operate this single segment as a sightseeing line.

Competition with the Tamako Railway — absorbed by the Musashino Railway in 1940 — intensified once the Tamako line was completed through. Its terminus, opened in 1936, stood right beside Murayama-Teisuiike-mae and was even given the confusingly similar name "Murayama-Teisuiike Station." Seibu raised its own station to full status on 27 January 1939 and on 1 March 1941 renamed it Sayama-kōen, and a fierce scramble for lake-bound tourists played out around the two neighbouring stations. As the Second World War intensified, tourist traffic fell away and the rivalry cooled; in 1943 the line briefly carried air-raid-protection materials under contract to Tokyo City, but as a sightseeing route it was designated a non-essential wartime line and was suspended on 10 May 1944, its track lifted. Amid wartime consolidation the old Seibu and the Musashino Railway were merged, becoming Seibu Agricultural Railway on 22 September 1945 (renamed Seibu Railway in 1946).

The line returned to service on 1 April 1948, after Seibu acquired a large tract of land around the reservoir in 1947 to develop a comprehensive amusement complex, the Higashimurayama Bunka-en; the reopening doubled as a means of carrying construction materials and visitors. The terminus, renamed Sayama-kōen before the war, reverted to a name close to its original as Murayama-Teisuiike Station. Soon a public bicycle-racing track, the Murayama Velodrome (today the Seibuen Velodrome), was added within the complex, and to serve it the company laid a branch from a new Noguchi Signal Box to a new Seibuen Station, opened on 23 May 1950 as a temporary station used only on race days.

The company came to regard Seibuen as central to its Bunka-en plans, while the old terminus at Murayama-Teisuiike — a station opened largely to spite the rival company that was now part of the same Seibu group — had become redundant; running trains toward both Seibuen and Murayama-Teisuiike also caused operating trouble at Noguchi Signal Box. With the support of the mayor of the local Higashimurayama town, the Noguchi Signal Box–Murayama-Teisuiike section (about 0.9 km) was abolished on 1 March 1951, Murayama-Teisuiike Station was merged into Seibuen and closed, and Seibuen was made a permanent station, creating the present alignment. On 25 March 1952, when the Murayama Line's Higashi-Murayama–Seibu-Shinjuku section was renamed the Shinjuku Line, this segment was separated and renamed the Seibuen Line.

In later years the line ran some six-car through services to and from Kokubunji over the Kokubunji Line, and at times eight-car through services to the Shinjuku Line including express and special-rapid workings. The Shinjuku Line through service ended after a derailment at Higashi-Murayama Station on 24 December 2011: the line was suspended to the last train that day, through running was halted from 30 December 2011, and the arrangement was formally abolished in the timetable revision of 30 June 2012. From the March 2019 revision the track layout at Higashi-Murayama was rebuilt in connection with grade-separation works, reversing the orientation of the trains and changing the line's stabling to via the Kokubunji and Haijima lines from the Tamagawa-jōsui depot. Today all trains operate as four-car shuttles within the line, roughly three an hour by day and four to five at peak.

• 1915The old Seibu Railway obtains a licence for the "Hakonegasaki Line" (Murayama Line), a Higashi-Murayama–Hakonegasaki extension that goes unbuilt for years.
• 19305 April: Higashi-Murayama–Murayama-Teisuiike-mae (provisional), 2.8 km, opens as part of the Murayama Line.
• 1931The parent Hakonegasaki Line concession is revoked by the Railway Ministry after repeated construction delays.
• 193927 January: Murayama-Teisuiike-mae is upgraded from a provisional to a full station.
• 19411 March: Murayama-Teisuiike-mae Station is renamed Sayama-kōen Station.
• 194327 October: a siding for materials transport is installed at Sayama-kōen under contract to Tokyo City.
• 194410 May: the Higashi-Murayama–Sayama-kōen section is suspended as a non-essential wartime line and its track is removed.
• 194522 September: the operator is merged into the Musashino Railway, becoming Seibu Agricultural Railway (renamed Seibu Railway in 1946).
• 19481 April: Higashi-Murayama–Murayama-Teisuiike reopens; Sayama-kōen Station is renamed Murayama-Teisuiike Station.
• 195023 May: the Noguchi Signal Box–Seibuen branch (0.5 km) opens; Seibuen is a temporary station for the velodrome, and both Murayama-Teisuiike and Seibuen operate for ten months.
• 19511 March: the Noguchi Signal Box–Murayama-Teisuiike section (about 0.9 km) is abolished, Murayama-Teisuiike Station is merged into Seibuen and closed, and Seibuen becomes a permanent station — forming the present alignment.
• 195225 March: with the Murayama Line's Higashi-Murayama–Seibu-Shinjuku section renamed the Shinjuku Line, this segment is separated and renamed the Seibuen Line.
• 201124 December: a derailment at Higashi-Murayama Station suspends the line to the last train; through running with the Shinjuku Line is halted from 30 December.
• 201230 June: the through service to the Shinjuku Line is formally abolished in the timetable revision.
• 201916 March: in connection with grade-separation works, the track layout at Higashi-Murayama is changed, reversing the orientation of the trains; stabling moves to the Tamagawa-jōsui depot via the Kokubunji and Haijima lines.