This is certainly more costume, but fun nonetheless.
However, a majority of them have to remove the thick make up and costumes eventually in order to go to work or school or function in society. Especially, for a traditionally monogenous society with the famous old proverb of "The nail that sticks up gets hammered down."
So this certainly doesn't represent the mainstream or majority in Japan. However it's quite a popular and growing subculture with many facets to consider.
Although, I think the ganguro gals might be more Shibuya if I'm not mistaken. I can be wrong, I haven't studied this culture in quite a while.