Yakuza also known as gokudō , are members of traditional organized crime groups in Japan. Today, the yakuza are one of the largest organized crime phenomena in the world. In the Western press they are sometimes called the "Japanese mafia," by analogy with other traditionally Italian-Sicilian organized crime groups of the same name.

Yakuza strength rises and falls according to the tides of Japanese society, with estimates of core membership ranging from 80,000 to more than 110,000 in the years from 1945 to 1996. Some authorities believe Japan's National Police routinely undercount the Yakuza, numbering only those names found in confiscated membership rolls, or recorded from routine police intelligence reports. Like the Sicilian Mafia and other underworld organizations, the Yakuza are formed into families.