Good point, but this is in the context of a country that is extremely densely populated. A controlled decrease of the population may be beneficial. I have a feeling that the Japanese elite are well aware of the danger and may be able to remedy the situation before it gets out of hand.
As a European I find it interesting that blacks comprise 61 percent of both perpetrators and victims and Hispanics make up most of the rest. And even more interesting is the fact that ethnicity is reported openly -- that would never happen in my country, even if most people would understand anyway that the majority of perpetrators are Arabs and Africans.