The Yakuza is quite the Old Boys Club. There are strict, highly sexist rules concerning women, who exist only as wives, girlfriends and mistresses of gang members. You would be hard-pressed to find a woman in a position of any kind of authority within the Yakuza.
While male Yakuza members get tattooed as a rite of initiation, proving their dedication and power, women are tattooed to indicate loyalty and obedience to the men they are involved with or to show their affiliation with the Yakuza as a whole.
The life of a Yakuza woman is a rough one. The beauty of their intricate tattoos often cover lives of abuse. At the very least, they spend their days and nights fully subservient to the whims and desires of the men they serve.