A detective who specialized in organized crime once told me a dark joke: What type of crime occurs when a member of the yakuza kills another gangster? Answer: destruction of property.
The joke perhaps reflects an unwritten premise of law enforcement in Japan: as long as gangs confine their conflict to other gangs, it's no big deal.
However, when the Yamaguchi-gumi — the country's largest organized crime syndicate, with about 23,400 known members at the end of 2014 if quasi-members are included — split into two factions on Aug. 27, the police were understandably concerned.