Zozotown, which swooped in as a little-known retail website and prodded once-reluctant Japanese consumers to shop online for clothes, is now facing stiff competition in the industry whose image it remade.

Arriving on the scene in 2004, the site made a killing selling clothes from shops such as Japanese boutique United Arrows and minimal French label A.P.C.

Zozotown¡¯s success turned its founder into one of Japan¡¯s richest entrepreneurs, and its name adorns a baseball stadium.