The yakuza is the world's largest organized crime syndicate, originating in Japan. They are notorious for their strict codes of conduct and organization. The modern yakuza organizations date back to the mid-Edo era, 1603-1868. They are organized into tekiya, those who primarily peddled illicit, stolen or shoddy goods, and bakuto, those who were involved in or participated in gambling.

The yakuza adopted the traditional Japanese hierarchical structure of oyabun-kobun where kobun owe their allegiance to the oyabun. The oyabun-kobun relationship is formalized by ceremonial sharing of sake from a single cup.

Members of yakuza gangs cut their family ties and transfer their loyalty to the gang boss. They refer to each other as family members - fathers and elder and younger brothers.