Wiktionary
n. 1 (context lang=en uncountable) A subculture of conspicuous consumption among young woman in urban Japan, typified by dyed hair, artificial suntan, platform boots, miniskirts, and expensive accessory. 2 (context lang=en countable) A member of this subculture.
Wikipedia
is a Japanese fashion culture which involves schoolgirls wearing an outfit based on their uniform, but with very short skirts. The short skirts are worn irrespective of the season (summer, winter or rainy). The girls may also wear loose socks, scarves and have dyed hair. The word "kogal" is anglicized from kogyaru, a contraction of kōkōsei gyaru (high school gal). The girls refer to themselves as gyaru (gals), although this word is applied to several other fashion looks as well.
Aside from the miniskirt or microskirt, and the loose socks, kogals favor platform boots, makeup, and Burberry scarves. They may also dye their hair brown and get artificial suntans. They have a distinctive slang peppered with English words. They are often, but not necessarily, enrolled students. Centers of kogal culture include the Harajuku and Shibuya districts of Tokyo, in particular Shibuya's 109 Building. Pop singer Namie Amuro promoted the style. Kogals are avid users of photo booths, with most visiting at least once a week, according to non-scientific polls. While critics condemned the gyaru as shallow, materialistic, and devoted to conspicuous consumption, admirers describe them as, "kindhearted, active young women in exuberant health, the women of today."