Wikipedia
is Japan's largest yakuza organization. It is named after its founder Harukichi Yamaguchi. Its origins can be traced back to a loose labor union for dockworkers in Kobe before World War II.
It is one of the largest criminal organizations in the world. According to the National Police Agency, it had 20,400 active members and 18,600 associated members in 2007. It is, by far, the largest of the boryokudan groups, and its membership encompasses roughly 45% of the 86,300 yakuza in the Japanese underworld. Leading members of the Yamaguchi-gumi number 102 people in total; 1 kumichō (組長; boss), 15 shatei (舎弟; younger brother) and 86 wakachū (若中; child) as of November 2005.
The Yamaguchi-gumi are among the world's wealthiest gangsters, bringing in billions of dollars a year from extortion, gambling, the sex industry, arms and drug trafficking, and real estate and construction kickback schemes. They are also involved in stock market manipulation and Internet pornography.
The Yamaguchi-gumi has its headquarters in Kobe, Japan, but it operates all across Japan and has overseas operations in Asia and the United States. Its current kumicho (Boss), Shinobu Tsukasa, has declared an expansionist policy—even making inroads into Tokyo, traditionally not Yamaguchi turf. They also have multiple groups working overseas.