The Yakuza is a Japanese organized crime group that has been in existence for more than 300 years. The word "yakuza" is often translated as "gangster" in English, referring to an individual involved in a Mafia-like criminal organization. Yakuza groups are headed by an oyabun or kumichō (family head) who gives orders to his subordinates, the kobun. 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.

Yakuza have a complex organizational structure. There is an overall boss of the syndicate, the kumicho, and directly beneath him are the saiko komon (senior advisor) and so-honbucho (headquarters chief). The second in the chain of command is the wakagashira, who governs several gangs in a region with the help of a fuku-honbucho who is himself responsible for several gangs. The regional gangs themselves are governed by their local boss, the shateigashira.

The Yakuza have been involved in a wide range of criminal activities, including gambling, loan sharking, drug trafficking, prostitution, and day-labor contracting. They have also been known to have ties to smuggling and have been involved in violent gang wars. Despite being illegal, the Yakuza remains a powerful force in Japanese society today, involved in everything from drug trafficking to money laundering.