At 6:50 of episode 25 of Great Teacher Onizuka, we see three girls bitching about the new school nurse Nao Kadena:
I have not seen even a glimpse of these three girls, until episode 25. The part which intrigues me is their appearance. I've not noticed anyone with such a unique appearance in the series.
Has there been any characteristic explanation regarding it? Is it make up, or something else?
It is called ganguro, which is very well known for its dark-tan makeup.
Ganguro (ガングロ) a fashion trend among young Japanese women that started in the mid-1990s, distinguished by a dark tan and contrasting make-up liberally applied by fashionistas.
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Ganguro instead tanned their skin, bleached their hair and used much colourful makeup in unusual ways.
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In ganguro fashion, a deep tan is combined with hair dyed in shades of orange to blonde, or a silver grey known as "high bleached". Black ink is used as eye-liner and white concealer is used as lipstick and eyeshadow. False eyelashes, plastic facial gems, and pearl powder are often added to this. Platform shoes and brightly coloured outfits complete the ganguro look. Also typical of ganguro fashion are tie-dyed sarongs, miniskirts, stickers on the face, and many bracelets, rings, and necklaces.
It is also a subculture of gyaru (gal), and developed into further styles like yamanba and manba since the 2000s.