Principal families

Although yakuza membership has declined following an antigang law aimed specifically at yakuza and passed by the Japanese government in 1992, there are thought to be more than 87,000 active yakuza members in Japan today. Although there are many different Yakuza groups, together they form the largest organized crime group in the world. Most yakuza members belong to five principal families

                                                  Yamaguchi-gumi family

                                                 Sumiyoshi-kai  family

                    
                                                   Inagawa-kai family

                                                 Aiizukotetsu-kai family

                                                         Toa-kai family

Organization and activities(yakuza)

During the formation of the yakuza, they adopted the traditional Japanese hierarchical structure of oyabun-kobun where kobun (lit. foster child) owe their allegiance to the oyabun (lit. foster parent). In a much later period, the code of jingi (justice and duty) was developed where loyalty and respect are a way of life.
The oyabun-kobun relationship is formalized by ceremonial sharing of sake from a single cup. This ritual is not exclusive to the yakuza—it is also commonly performed in traditional Japanese Shinto weddings, and may have been a part of sworn brotherhood relationships.
During the World War II period in Japan, the more traditional tekiya/bakuto form of organization declined as the entire population was mobilised to participate in the war effort and society came under strict military government. However, after the war, the yakuza adapted again.
Prospective yakuza come from all walks of life. The most romantic tales tell how yakuza accept sons who have been abandoned or exiled by their parents. Many yakuza start out in junior high school or high school as common street thugs or members of bōsōzoku gangs. Perhaps because of its lower socio-economic status, numerous yakuza members come from Burakumin and ethnic Korean backgrounds.
Yakuza groups are headed by an Oyabun or Kumichō (family head) who gives orders to his subordinates, the kobun. In this respect, the organization is a variation of the traditional Japanese senpai-kōhai (senior-junior) model. 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. The Yakuza is populated almost entirely by men, and there are very few women involved who are called "nee-san" (older sister). When the Yamaguchi-gumi (Family) boss (Kazuo Taoka) was shot in the early 1980s, his wife (Fumiko) took over as boss of Yamaguchi-gumi, albeit for a short time.
The Yakuza have a very 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.
Each member's connection is ranked by the hierarchy of sakazuki (sake sharing). Kumicho are at the top, and control various saikō-komon (senior advisors). The saikō-komon control their own turfs in different areas or cities. They have their own underlings, including other underbosses, advisors, accountants and enforcers.
Those who have received sake from oyabun are part of the immediate family and ranked in terms of elder or younger brothers. However, each kobun, in turn, can offer sakazuki as oyabun to his underling to form an affiliated organisation, which might in turn form lower ranked organisations. In the Yamaguchi-gumi, which controls some 2,500 businesses and 500 yakuza groups, there are even 5th rank subsidiary organisations.

Burakumin(yakuza)

The Burakumin are a group that is socially discriminated against in Japanese society. The burakumin are descendants of outcast communities of the feudal era, mainly those with occupations considered tainted with death or ritual impurity, such as butchers, executioners, undertakers or leather workers. They traditionally lived in their own secluded hamlets and ghettos. Discrimination against the Burakumin continues into the present day, a legacy of the Japanese feudal/caste system.
According to David E. Kaplan and Alec Dubro, burakumin account for about 70 percent of the members of Yamaguchi-gumi, the largest Yakuza syndicate in Japan^.
Mitsuhiro Suganuma, ex-officer of the Public Security Intelligence Agency, testified that burakumin account for about 60 percent of the members of the entire Yakuza.

yakuza

Yakuza also known as gokudōare members of traditional organized crime syndicates in Japan. The Japanese police, and Japanese media by request of the police, call them bōryokudan , literally "violence group", while the yakuza call themselves "ninkyō dantai" ( "chivalrous organizations")

Presumed origin	The Kabuki-mono
Creation	17th century
Actual number	86 300 members
Principal clans	Yamaguchi-gumi Sumiyoshi-kai Inagawa-kai Toa-kai Aizukotetsu-kai
Activities	Blackmail, illegal gambling, casinos, murder, prostitution, smuggling