The Seibu 10000 series (西武10000系) is an electric multiple unit (EMU) train type operated by the private railway operator Seibu Railway on limited express services in the Tokyo area of Japan since 1993.

[1] Branded as "NRA" or "New Red Arrow", the trains are used on Koedo services from Seibu-Shinjuku in Tokyo to Hon-Kawagoe.

They were formerly also used on Musashi and Chichibu services from Ikebukuro in Tokyo to Hannō and Seibu-Chichibu stations.

[3] A further three trainsets were delivered in 1994 and introduced on Chichibu services from Ikebukuro in Tokyo to Seibu-Chichibu on 15 October 1994.

Since then, the fleet of 10000 series has been used on limited express service on the Seibu Shinjuku Line.