The E231 series of the Musashino Line began operations in 2017, transferred from the Chuo-Sobu Line. A total of 34 train sets were introduced, becoming the main fleet of the line. From Nishi-Funabashi, it directly reaches the Keiyo Line, extending operations to Tokyo and Kaihin Makuhari, and it also runs to Omiya on the Tohoku Main Line and Hachioji on the Chuo Line via the "Shimosa" and "Musashino" services.
- Compatible with interior lighting kit Kato 11-211 (11-212)