I noticed many girls wearing their uniforms everywhere. Sometimes in the day when I thought they'd be in school. But I see them in their uniforms at Disneyland and in Harijuku shopping. Do they just like to wear them everywhere? Disneyland is a big school field trip destination, so those girls who are in uniforms are likely to be on field trips.
Why do the school girls wear their uniforms everywhere? - Tokyo Forum
For Japanese Girls, Uniforms Are Now Too Cool for School - WSJ
The Japanese school uniform is modeled in appearance similar to that of the European-style naval uniforms and was first used in Japan in the late 19th century, replacing the traditional kimono. There are many types of uniforms that range from standard to unique ones varying in the ensembles used. Japanese school uniforms have been around for years. Its first model was similar to the appearance of European-style naval uniforms.