I agree with Nyororin, do not romanticize the yakuza. They are a part of organized crime. The fundamental structure is like the presentation of the Italian mafia in The Godfather or Goodfellas: They have to have a presence, and a positive one in their immediate community. It's once you get mixed up with their business you have things to worry about. (Think of the restaurant owner in Good fellas who asks for a loan from the local Don, and ends up having his business liquidated and finally torched.)
This is from famous film director Juzo Itami's page in
Wikipedia:
In 1992, Itami was attacked, beaten, and slashed by five members of the Goto-gumi, a Tokyo yakuza gang, who were angry at his portrayal of yakuza as bullies and thugs in his film Minbo no Onna. This attack led to a government crackdown on the yakuza. His subsequent stay in a hospital inspired his next film Daibyonin, a grim satire on the Japanese health system.
If you would like to know more watch the movie Minbo no Onna. It is a crash course on how a yakuza gang can make life hell for a business that doesn't kow-tow to them (in this case a hotel).
Minbo - Wikipedia, the free encyclopedia