The Big Head's main business was selling goods and fake medicines between the local villages and in the city and towns they controlled the business of the small street stalls. The stall owners payed protection money to the Big Head and normally the Big Head yakuza protected common people from the outrages of the samurai.
The Big Head was organized like a family with the boss as father of his underlings. There were only three important rules in the Big Head: not to do anything with the wife of another Big Head, not to talk about the Big Heads, and to obey the oyabun. If someone broke these rules, they were punished with death or exile. The Big Head were semi-officially recognized by the city's authorities and often the city's police asked for their help.