Seibu Toshima Line

The line was a project of the Musashino Railway, the predecessor of today's Seibu Railway. The company applied for a railway operating licence on 20 September 1926 and was granted it on 30 October 1926, for a route in Shimo-Nerima village in the former Kita-Toshima District. An application to begin construction followed on 9 December 1926. The short branch was intended from the outset to connect the existing Musashino Railway main line (the present Ikebukuro Line) at Nerima with the grounds of a large new recreation park then being developed nearby.

Construction was authorised on 28 June 1927 and work began on 5 September 1927. The line opened on 15 October 1927 as the Musashino Railway Toshima Line, running the 1.0 kilometre from Nerima to Toshima Station. Its purpose was passenger access to the Toshimaen amusement park, part of which had opened nearby in 1926, and from its first day the line served as the park's access route.

On 1 March 1933 the line's outer terminus, Toshima Station, was renamed Toshimaen Station after the amusement park it served. Neither Nerima nor Toshimaen Station is in Toshima Ward.

On 22 September 1945 the line became part of the Seibu Agricultural Railway (Seibu Nōgyō Tetsudō). On 15 November 1946 the route became the Seibu Toshima Line, the form under which it has operated ever since.

In service the Toshima Line is operated as an extension of the Ikebukuro Line. As of the March 2022 timetable revision, every train is a local service, and all but the first Toshimaen-bound train of the day, which starts at Nerima, run through between Toshimaen and Ikebukuro. At Nerima they connect with through trains to and from the Seibu Yūrakuchō Line. The parallel Toei Ōedo Line opened in part in 1991, and Toshima Line ridership has fallen sharply, especially since the subway was extended to Shinjuku in 1997.

Station numbering was introduced across all Seibu Railway lines during the 2012 fiscal year. The two Toshima Line stations were given numbers prefixed with the letters "SI", the same prefix used on the Ikebukuro Line, formally designating the Toshima Line as a branch of that line. Nerima carries the number SI06, shared with its place on the Ikebukuro Line, and Toshimaen is SI39.

2 stations tracked on the map, listed alphabetically. Select any to read its page.

• Nerima練馬
• Toshimaen豊島園

• 192620 September: the Musashino Railway applies for a licence for the line; the licence is granted on 30 October and a construction application follows on 9 December.
• 192715 October: the line opens as the Musashino Railway Toshima Line, running 1.0 km from Nerima to Toshima Station (construction authorised 28 June, begun 5 September).
• 19331 March: Toshima Station is renamed Toshimaen Station after the adjacent amusement park.
• 194522 September: the line becomes part of the Seibu Agricultural Railway.
• 194615 November: the route becomes the Seibu Toshima Line.
• 199110 December: the parallel Toei Ōedo Line opens its first section, Hikarigaoka–Nerima, beginning the competition that would reduce Toshima Line ridership.
• 199719 December: the Toei Ōedo Line is extended from Nerima to Shinjuku, intensifying the loss of Toshima Line passengers.
• 200012 December: the full Toei Ōedo Line opens, completing the competing route toward central Tokyo.
• 2012Station numbering is introduced across Seibu Railway during fiscal year 2012; the Toshima Line stations are prefixed 'SI', designating the line as a branch of the Ikebukuro Line.
• 202031 August: the Toshimaen amusement park, which the line was built to serve, closes permanently after about 94 years.