[2] As of 1 April 2015[update], the fleet consists of eight 10-car sets, numbered 9101 to 9108, based at Musashigaoka depot for use on Seibu Ikebukuro Line workings.

[2] Beginning in 2020, the 9000 series fleet was shortened to four-car formations and modified to accommodate driver-only operation for use on the Tamako Line.

[4] As of 15 June 2021,[update] the entire fleet has been modified for Tamako Line operation,[5] excluding sets 9101, 9106, and 9107, which were scrapped beforehand.

From July 2014, set 9103 was repainted in a "Red Lucky Train" livery in collaboration with the private railway operator Keikyu.

[6] Set 9103 was repainted in an all-over red livery after it was modified for Tamako Line operation.