Fukutoshin Line

The line began as "Line 13," a corridor recommended on 1 March 1972 in Urban Transit Council Recommendation No. 15. As first laid out it was to run from Shiki in Saitama via Wakōshi, Narimasu, Mukaihara, Ikebukuro and onward to Shinjuku, with possible later extension to Shibuya, Shinagawa and Haneda Airport, and with the Wakōshi–Mukaihara stretch sharing track with the planned Line 8 (the Yūrakuchō Line). The new route was conceived to relieve congestion along the corridor and to give convenient through-service between Tokyo's north-west, its south-west and the central districts strung along the Yamanote Line.

Because the Yūrakuchō Line was being built first, the two lines' shared northern section was constructed together to save cost. The Kotake-Mukaihara–Ikebukuro stretch was procedurally treated as a quadruple-tracked extension of the Yūrakuchō Line and, to save land, was built not as four parallel tracks but as a two-level tunnel, the upper deck for the Yūrakuchō Line and the lower deck reserved for Line 13. The upper Yūrakuchō Line deck opened in June 1983, and by August 1985 the lower Line 13 structure as far as Ikebukuro was structurally complete, though it stood unopened for years. A second government committee — Transport Policy Council Recommendation No. 7, on 11 July 1985 — fixed the line's southern terminus at Shibuya.

The planning then split sharply in two. The far north was dealt with by improving the parallel Tōbu Tōjō Line and beginning through-service over the Yūrakuchō Line, so that part of the original Line 13 became unnecessary. To relieve crowding west of Ikebukuro, the finished lower tunnel between Kotake-Mukaihara and Ikebukuro was brought into service early, opening on 7 December 1994 as the Yūrakuchō New Line (有楽町新線); trains ran non-stop, the intermediate Senkawa and Kanamechō stations were bypassed, and the terminus was signed as "New Line Ikebukuro." The line's brown colour first appeared at this stage. For the southern half, the Ikebukuro–Shibuya licence — applied for back in 1975 alongside the Wakōshi–Narimasu section but withheld in 1976 — remained in limbo for over two decades.

That deadlock broke only when the government adopted an emergency economic package in late 1998 and secured construction funds for Line 13, judging that the link would invigorate the local economy and ease crowding on the Yamanote and Saikyō lines. A fresh licence application was filed on 17 December 1998, the Type-1 railway business licence for Ikebukuro–Shibuya was obtained on 25 January 1999, and construction of that section began on 15 June 2001. During the works the operator, the Teito Rapid Transit Authority (Eidan), was privatised on 1 April 2004 and its construction role passed to the newly formed Tokyo Metro. The 3.2-kilometre new tunnel through Zōshigaya, Shinjuku-sanchōme and Meiji-Jingūmae employed shield-driven and cut-and-cover methods and a newly developed compound-circular twin-track shield on the Meiji-Jingūmae–Shibuya stretch; an extra station, Kita-sandō, was added to the original plan in May 1999.

On 24 January 2007 the line was given its name — "Fukutoshin Line" was chosen from staff submissions over candidates such as "Meiji-dōri Line" and "Shibuya Line" — and the names of the seven new stations between Ikebukuro and Shibuya were announced. The whole line opened on 14 June 2008, three months later than the originally planned March date. With the opening, the Yūrakuchō New Line section between Kotake-Mukaihara and Ikebukuro was absorbed into the Fukutoshin Line, the "New Line Ikebukuro" name was dropped, and the long-bypassed Senkawa and Kanamechō stations entered service. Through-running with the Tōbu Tōjō Line and, via the Seibu Yūrakuchō Line, the Seibu Ikebukuro Line began the same day. The first weeks were rocky: a tangle of through-services centred on Kotake-Mukaihara, mixed eight- and ten-car trains and unfamiliar crews produced delays of up to thirty minutes that spilled onto the connecting Tōbu and Seibu lines.

The line was soon woven into one of the Tokyo region's largest through-running networks. On 16 March 2013 the Tōkyū Tōyoko Line moved to share the line's Shibuya terminus, and from that day most trains have run through onto the Tōyoko Line and the Yokohama Minatomirai Railway's Minatomirai Line, terminating at Motomachi-Chūkagai in Yokohama — a rare case of a Tokyo Metro train running over four companies' tracks. A further extension came on 18 March 2023, when the opening of the Tōkyū Shin-Yokohama Line and Sōtetsu Shin-Yokohama Line let trains continue onto the Sōtetsu network, with many express services reaching as far south as Shōnandai. Through these links the Fukutoshin Line now anchors a six-operator network stretching from Ogawamachi and Kawagoe in western Saitama to Yokohama and beyond into central Kanagawa.

• 19721 March: Urban Transit Council Recommendation No. 15 adds urban high-speed Line 13 (Shiki–Wakōshi–Mukaihara–Ikebukuro–Shinjuku).
• 19752 September: licence applications filed for the Line 13 Wakōshi–Narimasu and Ikebukuro–Shibuya sections.
• 197611 August: the Wakōshi–Narimasu licence is granted, but the licence for the Ikebukuro–Shibuya section is withheld.
• 198324 June: Narimasu (now Chikatetsu-narimasu)–Ikebukuro opens (as the Yūrakuchō Line), on the upper deck of the shared two-level tunnel.
• 198511 July: Transport Policy Council Recommendation No. 7 sets the line's southern terminus at Shibuya; by August the Line 13 structure to Ikebukuro is complete but unopened.
• 198725 August: the Wakōshi–Narimasu section opens.
• 19947 December: Kotake-Mukaihara–Ikebukuro opens as the Yūrakuchō New Line; trains run non-stop and Senkawa and Kanamechō stations are bypassed.
• 199817 December: after the government secures construction funds in an emergency economic package, the licence for the Ikebukuro–Shibuya section is re-applied for.
• 199925 January: the Type-1 railway business licence for the Ikebukuro–Shibuya section is obtained.
• 200115 June: construction of the Ikebukuro–Shibuya section begins.
• 200229 January: through-service with the Tōkyū Tōyoko Line is decided.
• 20041 April: the operator, the Teito Rapid Transit Authority (Eidan), is privatised; the construction project passes to the newly formed Tokyo Metro.
• 200724 January: the line is named the 'Fukutoshin Line', chosen from staff submissions, and the names of the seven new Ikebukuro–Shibuya stations are announced.
• 200814 June: the Ikebukuro–Shibuya section opens, completing the line; the Yūrakuchō New Line is absorbed, Senkawa and Kanamechō enter service, and through-running with the Tōbu Tōjō Line and (via the Seibu Yūrakuchō Line) the Seibu Ikebukuro Line begins — three months later than originally planned.
• 201316 March: the Tōkyū Tōyoko Line moves to share the Shibuya terminus; through-services begin onto the Tōyoko Line and the Minatomirai Line to Motomachi-Chūkagai in Yokohama.
• 202318 March: with the opening of the Tōkyū Shin-Yokohama Line and Sōtetsu Shin-Yokohama Line, through-service to the Sōtetsu network begins, many express trains reaching Shōnandai.