Setagaya Line

The line is the last surviving fragment of the old Tamagawa Line network, the streetcar system built by the Tamagawa Electric Railway (玉川電気鉄道), nicknamed "Tamaden." The present Setagaya Line corridor began as a branch of that network: on 18 January 1925 the company opened the section between Sangen-jaya and Setagaya as the Shimotakaido Line (下高井戸線), and on 1 May 1925 it completed the route by opening the remaining Setagaya–Shimo-takaido section. The branch ran on its own reserved track rather than down the middle of a road, a characteristic that would later prove decisive for its survival.

On 10 March 1938 the Tamagawa Electric Railway was absorbed by the Tokyo-Yokohama Electric Railway (東京横浜電鉄), the forerunner of today's Tokyu, and its lines were reorganised as the Tamagawa Line (玉川線). The "Tamaden" name stuck in popular usage and is still sometimes heard today. Over the following years several minor stops on the branch were rationalised away — Gōtokuji-mae and the old Miyanosaka station closed on 15 July 1945, and Rokushojinja-mae and Shichikenchō closed on 1 September 1949 — leaving broadly the ten-station alignment seen now.

The decisive moment came on 11 May 1969, when Tokyu abolished the main Tamagawa Line between Shibuya and Futako-tamagawaen, whose street-running tracks had become entangled with worsening road traffic. The Shimotakaido branch, which barely ran on roads at all, was spared and renamed the Setagaya Line. The closure cut the branch off from the Tamagawa Line's Ōhashi depot, so a new depot was built beside Kamimachi station, and the stations that had carried a "Tamaden" prefix — Wakabayashi, Yamashita and Matsubara — took their present plain names. The withdrawn street-running cars that had also served the Tamagawa Line were gradually retired.

For several years the Setagaya Line was an isolated route with no physical connection to the rest of the Tokyu network. That ended in 1977, when the New Tamagawa Line — the Shibuya–Futako-tamagawaen subway that today forms part of the Tōkyū Den-en-toshi Line — opened and restored an interchange, at Sangen-jaya, between the tram and Tokyu's heavy-rail system. The Setagaya Line also remains the only rail or tram route in the whole of Tokyu's history never to have met or crossed a Japan National Railways (or JR) line.

Modernisation followed in stages. On 11 November 1992 the Sangen-jaya terminus was moved westward, toward Shimo-takaido, as part of a redevelopment of the station forecourt, leaving an unusually short 0.3 km gap to the next stop at Nishi-taishidō. From 11 July 1999 the line began introducing the low-floor 300 series, raising platforms to eliminate the step at boarding; the platform-raising work was completed across every station after the last train on 10 February 2001, by which time the whole fleet had been standardised on the 300 series. Each of the ten two-car sets is painted a different colour, one of them in the green-and-cream "Tamaden" heritage livery.

The line retains a strong local character. It once had its own contactless smart card, "Setamaru," introduced on 7 July 2002 and usable only on the Setagaya Line; PASMO was adopted on 18 March 2007, and Setamaru was withdrawn from sale in 2012 and discontinued altogether on 30 September that year. All station lighting was converted to LED in 2013, and from 25 March 2019 the line switched to running entirely on renewable electricity — described as Japan's first railway operated all day on 100 percent renewable energy. A pair of trains is decorated in a "beckoning cat" (manekineko) theme in honour of nearby Gōtoku-ji temple, traditionally held to be a birthplace of the lucky-cat figure.

• 192518 January: the Tamagawa Electric Railway opens the Sangen-jaya–Setagaya section as the Shimotakaido Line, a branch of its network.
• 19251 May: the remaining Setagaya–Shimo-takaido section opens, completing the branch.
• 193810 March: the Tamagawa Electric Railway is absorbed by the Tokyo-Yokohama Electric Railway (forerunner of Tokyu); the branch becomes part of the Tamagawa Line.
• 194515 July: the Gotokuji-mae and former Miyanosaka stops are closed.
• 19491 September: the Rokushojinja-mae and Shichikencho stops are closed; Rokushojinja-mae is relocated and renamed Matsubara.
• 196911 May: Tokyu abolishes the main Tamagawa Line between Shibuya and Futako-tamagawaen; the surviving Shimotakaido branch is renamed the Setagaya Line, a new Kamimachi depot is built, and the 'Tamaden'-prefixed station names are dropped.
• 1977The New Tamagawa Line (the Shibuya–Futako-tamagawaen subway, now part of the Tokyu Den-en-toshi Line) opens, restoring an interchange at Sangen-jaya and ending the line's isolation.
• 199211 November: the Sangen-jaya terminus is moved westward in a station-forecourt redevelopment, leaving only 0.3 km to Nishi-taishido.
• 199911 July: the low-floor Tokyu 300 series is introduced and platforms are raised to remove the boarding step.
• 200110 February: platform-raising is completed at all stations after the last train, by which time the whole fleet has been standardised on the 300 series.
• 20027 July: the Setagaya Line-only smart card 'Setamaru' is introduced.
• 200718 March: the PASMO contactless card is introduced on the line.
• 2012Setamaru is withdrawn from sale and discontinued on 30 September, having been merged with PASMO.
• 2013All station lighting is converted to LED.
• 201925 March: the line switches to 100% renewable electricity — described as Japan's first railway run all day on renewable energy.