Michael Zielenziger makes an interesting statement in his book "Shutting out the Sun" (2006) by comparing the behavior of Japanese young women (and men) of selecting the "uniform" of a group they aspire to and of expecting a reaction/approval by this group, with the clashing of social high school cliques in the US. The difference of Japan, so he continues, lies in the fact that this ritual or process continues into adulthood and symbolizes on a more profound level the "infantilization" of adult Japanese who have become accustomed to following the demands imposed on them by others (and of not asserting a right of choice and self-determination).
His conclusion strikes me as somewhat simplified. The social dynamics are created by societal rules and rituals that are created and reproduced in a complex interaction between fashion, elites, education, corporate culture and sub-cultures. Following peer-pressure and group norms is not uniquely Japanese. The group norms in the US are different (emphasizing assertion and self-confident behavior), the punishments take other forms (but are not less severe). Still the observation is correct, the rituals continue longer and in a more regulated fashion. Yet, the magazines and channels for creating the styles copied and adapted are diverse and can be altered by the sub-cultures and external shocks.
Wearing any kind of brand makes you feel more self-confident by assuring you the consent and approval of a group. Identity choices are the selection among offered possibilities. These "roles" are not only present in high school or university life but continue for the "shakaijin" (members of society), giving them "roles" or personalities among which to select. These "types" exist in the West, too. Maybe their signs and codes are not as explicitly codified and published in magazines, or discussed and as widely known as in Japan. If that is true remains to be debated.
Magazine breakdown for women under 30 (MEKAS): http://mekas.jp/en/tutorials/132.xhtml#1
for women over 30: http://mekas.jp/en/tutorials/320.xhtml#1
