隈研吾
One four-car set was modified from set 4009 into a tourist train called the 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. The interior and exterior design of the train was overseen by architect Kengo Kuma.