harajuku is a small district of tokyo where teens and young adults shop and hang out to explore their own fashion trends. i.e. visual kei
, elegant gothic lolita
so a harajuku girl is a young, female participant in this fashionable subculture.
the term "harajuku girl" may have been coined by pop singer gwen stefani, but should not be associated with her beyond the title of one of her 'songs' as she is a poser
and knows less about tokyo than a wapanese