In Japan, costume roleplaying or cosplay is an everyday 'normal' event. It is not unusual to see teens in groups, all dressed up as their favorite anime character, J-pop singer or fantasy movie idol. (Though I said normal, others find it silly but still brings fascination among viewers.)
It is very likely that you will enter a café or restaurant in Tokyo's Akihabara district with waitresses dressed also as a popular anime character, a schoolgirl uniform or other sexy costumes. If you are into cosplaying, you can go on Sundays at the Harajuku district to socialize with like-minded anime fans, cosplayers, girls styled as punks, gothic, lolita and more.
This phenomenon, if rightly termed so, has caused a lot of business opportunities to open. From designers to tailors, to endorsements to contests and shops particularly selling costumes. No wonder cosplay and discount costumes shop are prominent in Tokyo. Next time you visit Tokyo, be sure to drop by one of those shops and get yourself a pair and show off! ;-)