Seibu Railway 101 series appeared in 1969 with the opening of the Seibu-Chichibu Line.
Equipped with a high-output motor and decelerating brake suitable for running on mountain lines, it has developed into a commuter train that represents Seibu. In 1979, the new 101 series was born with minor changes such as the front design, and in 1996, the beige around the windows was changed to a new paint color that was abolished. The new 101 series is still active in the branch section of Seibu Railway.
- Compatible with interior lighting kit Kato 11-211 (11-212) and Kato 11-213 (11-214)