Keiō Keibajō Line

As its name ("racecourse line") indicates, the line exists to carry passengers to the Tokyo Racecourse. Apart from the area around Higashi-Fuchū, most of the route lies within the Hachiman district of Fuchū, and along the way it crosses the approach path of the Musashi Kokufu Hachimangū shrine; the torii gate seen there was donated by Keiō. The line's operations are unusual in that the timetable, rolling stock and crewing arrangements differ sharply between weekdays, weekends and holidays, and days when racing is held at the Tokyo Racecourse.

The line opened on 29 April 1955, when the 0.9-kilometre section between Higashi-Fuchū and Fuchū-Keiba-Seimon-mae began operation. At opening the line was electrified at the low voltage of 600 V DC then in use on the Keiō network. On 4 August 1963 the overhead-line voltage was raised to 1,500 V DC, bringing the line up to the higher standard. On the day before that conversion, 3 August 1963, a surviving double-cab Deha 2400-type car made its last single-car run on the line.

Because the racecourse generates uneven demand, the line has long relied on flexible, demand-led operation. Ordinarily, shuttle trains run back and forth between Higashi-Fuchū and Fuchū-Keiba-Seimon-mae, with about four to six services an hour during the weekday morning peak and three an hour through the day and evening. The last trains are remarkably early — the final departures leave in the ten o'clock hour in the evening — which makes the line the earliest to finish service of any on the Keiō network.

On 28 July 1999 driver-only "one-man" operation was introduced on the weekday in-line shuttle trains, an urban-style arrangement in which fares are not collected on board. Operation has since used short two-car sets converted for one-man running, although conductors still ride on the first and last trains of the day and whenever a substitute set has to be used. On 2 October 2011 the line brought its Keiō ATC (automatic train control) signalling into use.

When racing is held at the Tokyo Racecourse — broadly on weekends and some public holidays in late January to mid-February, mid-April to June, and October to November — services are greatly augmented, with frequency raised to six trains an hour, roughly one every eight to twelve minutes, from the morning into the late afternoon. On race days, temporary limited expresses and express trains run through to Shinjuku over the Keiō Line, and main-line expresses make special stops at Higashi-Fuchū to connect with the branch.

To reflect this race-day pattern, new through services were added in the 2010s and 2020s. From 21 April 2018 a temporary Semi Special Express ran in the up direction only; it was discontinued on 20 February 2022 when the Semi Special Express category was merged into the Special Express. From 23 April 2022 a temporary Special Express, again up-direction only, began running. Temporary through trains to Shinjuku had earlier been suspended during the COVID-19 pandemic, when public racing was held without spectators, and resumed in April 2022.

Away from race days, the Fuchū-Keiba-Seimon-mae terminus sees relatively few passengers, and its platforms are unusually wide so as to handle race-day crowds. For both reasons the station and the line are frequently used as filming locations — Fuchū city and Keiō both run location services — and television commercials, music videos, films and television dramas are often shot there, including in-train scenes. An earlier rail approach to the racecourse had been provided by the Shimokōbara Line, a branch of the Japanese National Railways' Chūō Main Line.

• 195529 April: the 0.9 km Higashi-Fuchū–Fuchū-Keiba-Seimon-mae section opens, electrified at 600 V DC.
• 19633 August: a surviving double-cab Deha 2400-type car makes its last single-car run on the line, the day before the voltage conversion.
• 19634 August: the overhead-line voltage is raised to 1,500 V DC.
• 199928 July: driver-only (one-man) operation begins on the weekday in-line shuttle trains.
• 201131 January: the 6000-series one-man-converted sets are retired, ending their weekday one-man duties (in use since 1999); the 7000 series takes over.
• 20112 October: Keiō ATC (automatic train control) signalling is brought into use.
• 201322 February: station numbers are introduced (KO23 Higashi-Fuchū, KO46 Fuchū-Keiba-Seimon-mae).
• 201821 April: a temporary Semi Special Express begins running on race days, in the up direction only.
• 202220 February: the temporary Semi Special Express is discontinued when the Semi Special Express category is merged into the Special Express.
• 202223 April: a temporary Special Express begins running on race days, in the up direction only, as race-day through services resume after the COVID-19 spectator restrictions.