Kogal StyleKogal (ko-gyaru) style is similar to the Valley Girl style in the USA. It is the school age version of the larger gyaru movement. It is from the 90s-early 2000s.
Extremely short skirts (achived by rolling the waist band), oversized sweaters, and baggy socks are the key to achieving this look. Hair is modified to look more "Western" with highlights and/or curls.
Books and Movies:
Please Tell Me! Galko-Chan (manga series)
Kogal page on the Gyaru Wiki
Bold, Blonde and Beautiful?: Gyaru Fashion and Style