The is a railway line of the Japanese private railway operator Seibu Railway. It originates at Ikebukuro Station, a large railway junction in north-western Tokyo, extending to northwest suburbs as far as Tokorozawa, Saitama, and nominally terminates at Agano Station. The Seibu Chichibu Line from Agano to Seibu-Chichibu Station is an extension. The operation is largely divided into two sections: from Ikebukuro to Hannō Station and from Hannō to Seibu-Chichibu Station. The section from Hannō to Seibu-Chichibu is single track, but every station except for Higashi-Hanno has passing loops, and trains may pass each other at any stop. There is also a passing loop inside a tunnel where the signal controls bi-directional operation. The rest of all the lines is double track with track gauge. Branch lines The Ikebukuro Line has three branches with through operation, apart from the Seibu Chichibu Line. Toshima Line length, with Local trains through from Ikebukuro. Seibu Yūrakuchō Line The bypass to Tokyo Metro Yūrakuchō Line/Tokyo Metro Fukutoshin Line, with Semi Expresses and Rapids from Hannō to Shin-Kiba Station/Motomachi-Chukagai Station, with Locals. Seibu Sayama Line Through trains are operated daily during off-peak hours. Special Limited Express "Dome" services are occasionally operated for baseball games of the Saitama Seibu Lions. Line data Tracks: 4-track: Nerima to Shakujii-kōen () 2-track: Ikebukuro to Nerima (), Shakujii-kōen to Hannō (), Kita-Hannō rail yard to Musashigaoka Rail yard () 1-track: the remainder Service pattern Abbreviations here are for the table below, not formally used. Stops at all stations. The longest operations are Ikebukuro to Hannō, through to Seibu Kyūjō-mae on Sayama Line, through to Toshimaen on Toshima Line. Also through from Tokyo Metro Yūrakuchō Line to Kotesashi and Hannō. Major sections of service are from: Ikebukuro to Toshima-en and Hōya; from Shin-Kiba on Tokyo Metro Yūrakuchō Line to Hōya, Kiyose and Kotesashi and from Motomachi-Chūkagai on the Minatomirai Line to Shakujii-kōen, Hōya, and Hannō. (SE) Operated all day. Longest from Ikebukuro to Hannō and Seibu Kyūjō-mae. Through from Yūrakuchō Line to Hannō. (CSE) Morning hours only, one direction up from Kotesashi to Ikebukuro. (Ra) Morning and evening hours to/from Ikebukuro, daytime through to Yūrakuchō Line. Longest to Hannō (seasonally one service a day to Seibu-Chichibu) and Seibu Kyūjō-mae. (CE) Morning hours only, one direction up from Hannō to Ikebukuro. (Ex) All day operation, from Ikebukuro to Hannō. (RE) Morning rush hour from Hannō to Ikebukuro, daytime to and from Hannō/Kotesashi