Japanese people are human and the base morality that evolution has endowed us with. This divides humanity into two groups, in group and out group. Morality only applies to the in group. It takes a lot of acculturation and education to expand an individual's conception of the in group is, from family/tribe to nation/culture to humanity. As such, any sub-culture that can take over the public sphere of a culture will have little difficulty getting people to dehumanise the other, and once they're dehumanised people have little more difficulty committing atrocities than they do slaughtering animals.
As you may have noted none of this is specific to Japanese culture. That's because in this respect we're a lot weirder than they are in historical perspective.
If you want a good overview of man's violence towards man and it's decline I recommend Better Angels of Our Nature, Stephen Pinker.
Japanese people are human and the base morality that evolution has endowed us with. This divides humanity into two groups, in group and out group. Morality only applies to the in group. It takes a lot of acculturation and education to expand an individual's conception of the in group is, from family/tribe to nation/culture to humanity. As such, any sub-culture that can take over the public sphere of a culture will have little difficulty getting people to dehumanise the other, and once they're dehumanised people have little more difficulty committing atrocities than they do slaughtering animals.
As you may have noted none of this is specific to Japanese culture. That's because in this respect we're a lot weirder than they are in historical perspective.
If you want a good overview of man's violence towards man and it's decline I recommend Better Angels of Our Nature, Stephen Pinker.