History
Seibu-Shinjuku Station opened on 25 March 1952 as a temporary terminus when Seibu's Murayama Line (then renamed the Shinjuku Line) was extended south from Takadanobaba in Kabukichō 1-chōme, Shinjuku. Seibu had received a 1948 licence to push the line through to JR Shinjuku's east-side concourse and helped fund the 1964 Shinjuku Station Building (today's Lumine Est), but the 8-car platforms that operations now required could not fit the constrained alignment, and on 25 March 1965 the operator formally withdrew its through-running plan. The present 25-storey terminal with the Shinjuku Prince Hotel and PePe shopping centre opened on 3 March 1977, and the north entrance followed in October 1980.
History summarized from Japanese & English Wikipedia · last reviewed 2026-05-18.
Notes
When the line was first laid towards Shinjuku, Seibu's claim to the alignment came from its ownership of the Shinjuku-line streetcar (Seibu Kidō Line, Shinjuku–Ogikubo, suspended in 1951) — the company kept the licence rather than transferring the track to Tokyo, and used that paper-right to justify the planned southern push.