Even though Japan is extremely diverse when it comes to fashion, there are 2 kinds of outfits that you will definitely recognize walking through the streets: suits and school uniforms (制服). Most western readers might already have seen Japanese school uniforms in anime, they have become a fixed part of Japanese culture and identity.
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. Today, school uniforms are common in many of the Japanese public and private school systems.
Various schools are known for their particular uniforms. Uniforms can have a nostalgic characteristic for former students, and are often associated with relatively carefree youth.
Uniforms are sometimes modified by students as a means of exhibiting individualism, including lengthening or shortening the skirt, removing the ribbon, hiding patches or badges under the collar, etc.
Regardless of what type of uniform any particular school assigns its students, all schools have a summer version of the uniform (usually consisting of just a white dress shirt and the uniform slacks for boys and a reduced-weight traditional uniform or blouse and tartan skirt with tie for girls) and a sports-activity uniform (a polyester track suit for year-round use and a T-shirt and short pants for summer activities).
It is normal for uniforms to be worn outside of school areas, however this is going out of fashion and many students wear a casual dress. While not many public elementary schools in Japan require uniforms, many private schools and public schools run by the central government still do so.
Now you know about the uniform situation in Japan, if you see students on the street, greet them, they’re working hard.