School girls with mini skirts, tanned skin and bleached hair. Teenagers sporting platform boots, Hawaiian themed clothes, and violently coloured streaks of pink, blue, orange in otherwise bleached brown locks. Young women in their twenties bedecked in denim, flashy gold jewellery and stiletto heels. Welcome to Shibuya, Tokyo in the early noughties.

Japan is infamous for its fashion and street styles. Fashionistas the world over know of Harajuku girls and gothic Lolita styles, extraordinary outfits which anywhere else would look incongruous to say the least, but on the streets of Tokyo are so everyday Japanese eyelids barely bat at the sight.

Except for one fashion style, less well known to the wider world, one which has caused uproar in Japanese media and society. They are the gyaru girls, those for whom just wearing the clothes isn't enough, the skin, hair and often lifestyle are also along for the ride.

What is a gyaru? The term is derived from the American 'gal', suggesting a relaxed, cool young woman, and while it could have been employed by the girls themselves to depict their style, its early usage appears to have been mostly by Japanese media. Gyaru style is identifiable from the mid-1990s, pioneered by the ko-gyaru (the ko coming from kodomo, meaning 'child'), savvy schoolgirls who raised their skirt hemlines to ever more indecent heights, and sported enormous baggy socks which hung around their calves. It was with the kogyaru that the fashion for tanning skin, and bleaching hair, a staple of almost all gyaru styles, began.

From kogyaru, a variety of styles began to develop. Some took the basic gyaru style to extremes, tanning skin to ever darker shades, bleaching hair to white or grey, and starting a trend for using white eyeliner around the eyes, combined with white lipstick, creating nothing so much as a 'reverse-panda'-like appearance. These girls were labelled ganguro ('blackface') and yamanba ('mountain hag'), by the male-dominated Japanese press, a clear indication of extreme dislike for the style. They wore neon-bright colours, provocatively short mini skirts and strappy tops, and perilously high platforms.

Ganguro and yamanba died out around 2000, but several years later, a new version of the yamanba style flung itself with admirable lack of social awareness onto the scene. These were the manba gyaru, a newer, brasher, bigger version of yamanba. For these girls white eyeliner and lipstick weren't enough, white eye shadow up to the eyebrows, down the bridge of the nose, and across the cheekbones were now de rigueur. And why stop there? Glittery eye make up, and cute stickers plastered around the eyes became popular as did extreme hair colours, and equally outlandish clothing.

Manba however were not as concerned about style as their predecessors, comfort for the first time was becoming a priority, and manba in sweatpants, pyjamas, and enormous costumes of cute cartoon characters and animals swept the scene. For these girls, being out and having fun was most important. Why go home, when you could sit in your comfy outfits on the streets of Tokyo, and be with your friends?

Manba also divided into ever more precise subsets of style. Romanba were interested in frilly, 'romantic' dresses, and princess-like styles, Banba, aimed to look just like Barbie dolls, and Coconba only wore clothes from the Japanese Cocolulu label.

Post-manba, gyaru styles have become somewhat more demure. The tanned skin largely remains, but lighter, hair is still bleached, but only to lighter shades of brown, hot pants, mini skirts, and strappy tops are still ubiquitous, but in more sophisticated styles. Older girls, in their mid to later twenties, who want to return to the gyaru fashions, have created a more adult version of the gyaru look, and hime-gyaru, or princess-gals, are obsessed with looking like, well, princesses, in frilly dresses, enormous hair teased into endless curls, and jewels on every available accessory.

Given the wide variety of imaginative gyaru styles, what binds them together, what makes a gyaru a gyaru? One important factor for being a gyaru is an element of sexiness, present even in the princess-gal styles. Compared to the more common Japanese fashions, with an emphasis on plain styles, gentle colours, covering up and layers, layers, layers, gyaru are provocative, open, even brazen in their sexuality. Where in the mainstream fashion magazines, Japanese girls pose demurely, in discreet and lady-like positions, gyaru magazines have their models every which way, legs apart, chests out, sex symbols in an otherwise prudish fashion world.

Another binding factor for the gyaru is the Tokyo town of Shibuya, a hub of activity, fashionable shops, famous clubs, and the meeting place, even living place, of any self-respecting gyaru and her friends. And then there is the phenomenon of Para Para, a dance consisting of robotic movements, to a background of frenetic Euro-beats. Gyaru of all kinds come together in groups to dance Para Para, learning the latest moves from popular DVDs, before performing them together at clubs. Almost always performed in groups, the dance requires a unity of movement an Olympic synchronised swimming team would admire.

So what has the rest of Japan made of the gyaru styles? Rather unsurprisingly, given the emphasis still on more traditional ideals of Japanese beauty-pale skin, black hair-the response was, initially at least, one of uproar. Male-dominated magazines have fumed at the brazenness of these girls in their choice to be, it seemed, deliberately ugly. Sharon Kinsella, in an article 'Black Faces, Witch and Racism against Girls', argues the term 'yamanba' (mountain witch) was used in the male-dominated Japanese press as a 'barely disguised slur'. Sharon Kinsella also sees the reaction of the media as 'unequivocal sexual rejection', and documents the headlines of some Japanese magazines, such as 'Big Survey of Aesthetic Taste: Teenage Witch Girls Should be Worried' in the current affairs magazine Spa!

Midori Nakano, writing in the respectable magazine Bungei Shunju, (later translated for the Japan Echo) insists that the key to the yamanba style lies in 'overwhelming others', making oneself 'dramatically ugly' if one is unattractive anyway. She says 'nothing about [the yamanba style] is pretty, elegant or stylish; the main effect, I would say, is to frighten'. As far as Midori is concerned, the young women who follow yamanba style 'almost seem to be wearing placards that say "I'm stupid".'

One Japanese man's reaction may reflect some public opinion. 'Gyaru? They're disgusting!' When asked why he thought gyaru dressed the way they did, he suggested that it was harder and harder for Japanese girls to make a statement in fashion 'so they get more and more extreme'.

Whatever conservative Japan might think of gyaru however, the popularity of it among young women, not to mention the entertainment factor of the trend, has been unavoidable. Daytime television programmes started including gyaru regularly on their shows, where much was made of their apparent stupidity and lack of social awareness. In one programme, a couple of girls were helped to 'graduate' from their gyaru status. After being shown that they were incapable at school, and unable to interact in the expected manner in working environments, the girls were taken for 'make-overs', changing their hair, make-up, and sense of style to one more 'acceptable' of a young Japanese woman. At the same time fashion magazines and companies creating products aimed at young women focused on gyaru trends as a key selling point.

Taking an outside perspective, it is an easy assumption to make that a gyaru's primary aim is to shock, to horrify, to rebel against societal norms, as is so common among teenagers of any country, any culture. Certainly Japanese media and sectors of society have jumped at the chance to point out the glaring differences between gyaru and other young women, forcing gyaru to be outsiders regardless of their real intentions.

The truth is rather different. In 2006 a Japanese drama about gyaru was aired on prime time television. It was aimed at a mainstream audience, written and produced by people who had previously worked on family friendly dramas and romantic comedies. 'Gyaru-sa' ('Girl Circle') is not a gritty, 'real' drama about the lives of gyaru today, but for all its rose tinting, it can illuminate a little on the truth about gyaru, and why they choose to dress and live the way they do.

The gyaru painted in the drama are, in reality, far from choosing to isolate themselves from society. Instead, if anything, they feel pushed away from the mainstream. Girls who choose to adopt the gyaru lifestyle may be dropouts from school, or feel unwanted at home, and so they turn to a being a gyaru to feel they belong somewhere. In one episode, several of the lead characters defend their choice to live as gyaru, and be part of a gyaru-sa, or society of gyaru who spend time together, dance Para Para, and organise events: