>. I was thinking more in terms of law enforcement and organized crime having a common cause in keeping foreign criminal syndicates out of Japan.
But let's be honest, the yakuza want to keep foreign criminal syndicates out of Japan because they want a monopoly on organized crime in Japan, not because they want to keep the Japanese people safe from foreign criminals. The yakuza deal in extortion, blackmail, drugs, guns, prostitution, human trafficking, all of the same criminal activity any other syndicate does. They may not be as openly violent as other mafias, but they're not nice people.
Claiming they have a "common cause" with the police is to assume that the police have no issue with crime in Japan so long as it's Japanese committing those crimes, which I think cannot be true, and would be a sign of dereliction of duty if it were. From what I understand the yakuza are losing power in Japan because the police have been effectively cracking down on them... they're not comrades in arms.
