A yanki is simply a subculture that was popular in Japan in the 80's and 90's. Moreover, it was basically the style of delinquent students. They were characterized by punch perms or pompadours, shaved eyebrows, altered school uniforms, popping squats, being poor students and causing violence or trouble. Yanki is a term that applies to both boys and girls. Although it is said some yanki would be recruited into the yakuza, or Japanese organized crime, this is not always true. Many yanki simply joined the regular workforce and lived regular, productive lives after high school. Being a yanki was simply a way to enjoy youth and lash out at society similar to the punk rock movement in the West.
Bosozoku had a similar style to yanki, but were known for their outrageous and illegally modified motorcycles. Their outfits usually consisted of long jackets or flight suits consisting of complicated kanji with multiple meanings. On occasion, bike gangs would gather and parade down streets interfering with traffic or waking people at night. In their heyday, both yanki and bosozoku were considered a menace to society.
The term "yanki" has been popularized in American culture through the movie Kamikaze Girls. However, in Japan it comprises whole a genre of comics, movies, and even music.