So apparently schoolgirls with high tech samurai gear is it's own genre, so I'm canonizing a new "gang."

Kyoko School for Girls. Originally a private school meant to cater to Burokun's relatively small upper class population.
Since the trouble with the Oni, they offered a kendo based self defense class, which bloomed into a popular sport. After a special fluff piece in [i]Street Samurai[/i], an surge of internet popularity spurred many of them to take their swords to the street. 

They've gained a sort of "neighborhood watch" status and is the only Ronin gang that is acting legally.