I'll keep refining the points of reference here RTF because I think you don't have the faintest clue what is happening in Japanese society. I will agree that one of the better points of Japanese society is the relative lack of violence and that this has come about partly because of the inaccesability of guns. Do you even know why this has come about?
RTF, by any analysis Japan was historically a violent society up until the 1945 surrender. The American occupation of Japan did many things and a lot of those things were good. The rich and peaceful society you see today was in many ways a result of how well Japan was administered after the war. But don't kid yourself. MaCarthur cut their balls off and made sure Japan will never threaten the West again. Part of that was to ensure that the populace didn't have access to weapons.
Be sure. The Americans didn't hand back this country until they were very sure that the Japanese were going to toe the line and believe me the Japanese love to toe the line. The Americans did such a good job that the same political party has controlled the country for 50 years. The Japan you see today is not so much a result of a monolithic culture but of a carefully controlled display of power. They have been able to set the agenda without any real opposition to their power so firmly entrenched was their mandate.
RTF, the fact is that most violence in the US is intra-culture - i.e. black on black, white on white and so on. It actually goes beyond this, most violence is between people who know each other, especially the really serious kinds. How does multiculturalism have anything to do with this?