Tobu Railway Co., Ltd.

Expansion came largely through mergers: the Sano Railway (today's Sano Line) in 1912, the Ōta Light Railway (today's Kiryū Line) in 1913, and on 22 July 1920 an equal merger with the Tōjō Railway — founded in 1911 as a separate company that nevertheless shared its president and head office with Tobu — which brought in today's Tōjō Main Line, with Tobu as the surviving company. Tobu ran its first electric train in 1924 between Asakusa (later Narihirabashi, today Tokyo Skytree Station) and Nishiarai. On 1 October 1929 the Nikkō Line was completed and Tobu carried out Japan's first long-distance electric-train operation of more than 100 km, adding a special Nikkō limited express on 10 October. On 25 May 1931 trains reached Asakusa Kaminarimon (today's Asakusa Station), connecting with the Tokyo Underground Railway, forerunner of the Ginza Line, which Hayakawa Noritsugu had opened with Nezu's backing; the Utsunomiya Line followed on 11 August 1931. The Jōshū Railway (today's Koizumi Line) was absorbed in 1937; then, after the land-transport coordination law that took effect in August 1938 made Tobu the integration entity for northern Kantō, wartime consolidation added the Shimotsuke Electric Railway (today's Kinugawa Line) and the Ogose Railway (today's Ogose Line) in 1943 and the Sōbu Railway (today's Noda Line) in 1944. Nezu Kaichirō II, president from July 1941 to June 1994, served the longest presidential tenure (52 years and 12 months) of any Tokyo Stock Exchange-listed company. Air raids in 1945, among them the Great Tokyo Air Raid, damaged areas along the Isesaki Line around Asakusa and along the Tōjō Main Line around Ikebukuro.

On 6 August 1948, by opening up some of the trains reserved for the Allied occupation forces, Tobu launched the Nikkō and Kinugawa limited expresses 華厳 (Kegon) and 鬼怒 (Kinu) — forerunners of today's "Kegon" and "Kinu" and the second limited-express operation by any Japanese private railway, after Kintetsu. The company listed on the First Section of the Tokyo Stock Exchange in May 1949, and in 1950 the network reached its historical maximum of 591.6 km. In October 1960 the 1720 series "Deluxe Romancecar" (DRC) entered service on the Nikkō and Kinugawa expresses as Tobu fought an intense market battle with Japanese National Railways for Nikkō tourism. Through-running from the Isesaki Line onto the Teito Rapid Transit Authority's (now Tokyo Metro) Hibiya Line began on 31 May 1962; steam operation ended on the Main Line network in 1966; the last tramway closed in 1968; and on 2 July 1974 the Kita-Senju–Takenotsuka section became the first quadruple-tracked stretch of any Kantō private railway. Tobu Zoo, a combined zoo and amusement park, opened on 28 March 1981, and the closure of the Kumagaya Line in June 1983 eliminated the network's last non-electrified line.

Later decades brought new partnerships and infrastructure: through services between the Kinugawa Line and the Yagan Railway's Aizu-Kinugawa Line from 9 October 1986, quadruple-tracking of the Tōjō Main Line between Wakōshi and Shiki with Yūrakuchō Line through-running from 25 August 1987, and the 100 series "Spacia" on the Nikkō and Kinugawa expresses from 1 June 1990. Grade separation and quadruple-tracking between Sōka and Koshigaya, completed on 25 March 1997 together with a major rebuilding of Kita-Senju Station, gave Tobu the longest quadruple-track section of any private railway in Japan. On 19 March 2003 the Isesaki Line began through-running with the Hanzōmon Line and the Tōkyū Den-en-toshi Line, and on 30 September that year Tobu abolished its freight business, until then the last surviving freight operation among Japan's major private railways. Through limited expresses to JR East — "Nikkō", "Kinugawa" and "Spacia Kinugawa" — followed on 18 March 2006, and on 14 June 2008, when the Fukutoshin Line opened, the Tōjō Main Line began through-running with it and gained the guaranteed-seating "TJ Liner"; that through network reached the Tōkyū Tōyoko and Minatomirai lines on 16 March 2013 and the Sōtetsu network on 18 March 2023.

Today Tobu operates twelve railway lines totalling 463.3 operating kilometres across Tokyo and the four prefectures of Saitama, Chiba, Tochigi and Gunma — excluding the JR Group, the longest rail network in the Kantō region and, since Nagoya Railroad's partial line closures of 2005, the second longest in Japan after Kintetsu (501.1 km, figures as of 2018). The network falls into two groups: the Main Line group, a tree of routes growing from the Isesaki Line trunk out of Asakusa and Oshiage that includes the Nikkō Line and the Noda Line (branded Tobu Urban Park Line since 2014), and the Tōjō group, formed by the Tōjō Main Line and the Ogose Line and running northwest from Ikebukuro; the two are physically connected only via the Chichibu Railway, which is used for ferrying rolling stock between them. As of 1 April 2016 Tobu operated 1,890 electric multiple unit vehicles, the third-largest fleet of any private railway operator in Japan after Tokyo Metro and Kintetsu.

Tobu is also the owner of Tokyo Skytree: construction of the tower by Tobu Railway and Tobu Tower Skytree Co. began on 14 July 2008 on the site of the former ground-level platforms at Narihirabashi, the "Tobu Skytree Line" branding for the Asakusa/Oshiage–Tōbu-Dōbutsu-Kōen section and systemwide station numbering arrived on 17 March 2012, and the Tokyo Skytree Town complex opened on 22 May 2012. More recently, the 500 series "Revaty" entered service on 21 April 2017; the steam-hauled "SL Taiju" began on the Kinugawa Line on 10 August 2017 with a Class C11 locomotive loaned from JR Hokkaido; the "Kawagoe Limited Express" began on the Tōjō Main Line on 16 March 2019 and the "TH Liner" on the Isesaki Line on 6 June 2020; the N100 series "Spacia X" debuted on 15 July 2023; and the new 80000 series entered Urban Park Line service on 8 March 2025. The core company of the roughly 80-member Tobu Group, whose interests span transport, retail, logistics, housing and leisure, Tobu is listed on the Prime Market of the Tokyo Stock Exchange, is a constituent of the Nikkei 225, and belongs to the Fuyō Group.

• 18971 November: Tobu Railway was incorporated, its corporate registration completed; it remains the oldest of Japan's major private railways still in operation.
• 189927 August: the first line, between Kita-Senju and Kuki — part of today's Isesaki Line — opened.
• 1905Amid poor business results, Nezu Kaichirō I was brought in as the company's first president; under him Tobu grew into one of the largest private rail operators in the Kantō region.
• 192022 July: Tobu carried out an equal merger with the Tōjō Railway, operator of today's Tōjō Main Line, with Tobu as the surviving company.
• 19291 October: the Nikkō Line was completed and Tobu carried out Japan's first long-distance electric-train operation of more than 100 km; a special Nikkō limited express began on 10 October.
• 193125 May: trains began serving Asakusa Kaminarimon Station (today's Asakusa Station), connecting with the Tokyo Underground Railway, forerunner of the Ginza Line; the Utsunomiya Line opened on 11 August.
• 19486 August: the Nikkō and Kinugawa limited expresses 華厳 (Kegon) and 鬼怒 (Kinu) — today's "Kegon" and "Kinu" — were launched by opening up some of the trains reserved for the Allied forces; this was the second limited-express operation by a Japanese private railway, after Kintetsu.
• 196231 May: the Isesaki Line began mutual through services with the Teito Rapid Transit Authority's (now Tokyo Metro) Hibiya Line.
• 19742 July: the Kita-Senju–Takenotsuka section of the Isesaki Line was quadruple-tracked, the first quadruple track of any Kantō private railway.
• 19901 June: the 100 series entered service on the Nikkō and Kinugawa limited expresses and was given the name "Spacia".
• 200319 March: the Isesaki Line began through-running with the Hanzōmon Line and the Tōkyū Den-en-toshi Line. 30 September: Tobu abolished its freight business, until then the last surviving freight operation among Japan's major private railways.
• 201217 March: the "Tobu Skytree Line" branding was introduced on the Asakusa/Oshiage–Tōbu-Dōbutsu-Kōen section, with station numbering across all lines; on 22 May the Tokyo Skytree Town complex — including the Tokyo Skytree tower begun in July 2008 — opened.
• 201721 April: the 500 series "Revaty" limited express entered service on the Isesaki, Nikkō, Kinugawa and Noda lines. 10 August: steam returned with the "SL Taiju" service on the Kinugawa Line, hauled by a Class C11 locomotive loaned from JR Hokkaido.
• 202318 March: the Tōjō Main Line began through services to the Sōtetsu network via the Fukutoshin Line, Tōkyū Tōyoko Line and Tōkyū Shin-Yokohama Line. 15 July: the N100 series "Spacia X" entered service on the Nikkō and Kinugawa expresses.