Plenty of looting by the Japanese in Nanking in 1937/38 (among other things).
Still, yes, the point that Japanese will not loot their own country during a time of natural disaster is certainly, from my limited experience of the Japanese, very true. They believe in the good of the community and will sacrifice themselves individually for the community good.
New Orleans and Haiti are examples of the socially disadvantaged using a natural disaster as an excuse for opportunistic acts to avenge a sense of past wrongs, or just individuals taking advantage in the absence of law and order with no sense of 'the good of the community'.
In Florida, when hurricanes roar through, signs indicating "looters will be shot" are not uncommon sights in coastal communities.