[1] As of 1 April 2016[update], the fleet consists of twelve four-car sets, numbered 4001 to 4023, based at Musashigaoka depot.

[1] The fleet was refurbished in 2002 for use on wanman driver only operation services on the Seibu Chichibu Line.

[1] One four-car set was modified from set 4009[3] into a tourist train called the Fifty-two Seats of Happiness (52席の至福, Gojūni seki no shifuku) for use on services operating between Seibu Shinjuku and Ikebukuro in Tokyo and Seibu Chichibu and Hon-Kawagoe in Saitama Prefecture, entering service from 17 April 2016.

[5] The automated on-board passenger announcements in Japanese use the voice of TV presenter Tomomi Kuno [ja], and the melody chimes accompanying the announcements were created by musician Minoru Mukaiya, who was formerly the keyboard player in the group Casiopea.

[2][6] From 16 January 2016, set 4015 received a special Hello Kitty livery as part of a campaign to promote tourism to the Chichibu area.