Police discourage autopsies that might reveal a higher homicide rate in their jurisdiction, and pressure doctors to attribute unnatural deaths to health reasons, usually heart failure, the group alleges. Odds are, it says, that people are getting away with murder in Japan, a country that officially claims one of the lowest per capita homicide rates in the world.
The fudging of stats is not only a Japanese trait. In Europe is also a custom to downgrade and even outright lie about a crime to avoid complicated investigations and lengthy trials to the point victims no longer bother to call their local police and just take it. Scotland Yard years ago was discovered grossly under reporting crime so the political animals would look to the constituents.
I simply do not trust statistics from other countries.