hayabusa1 said:
I wouldn't say that they are rare, but they are less common than what I regularly see in America. In general, Japanese girls are thinner and therefore have less 'curves'. Still, about 1/3 of Japanese or so are overweight and with that the accompanying big boobs. Big boobs on thin Japanese girls are rare.
Japanese girls tend to show off their legs rather than their chests.
The only reason big boobs are the "norm" in America is because the majority of women here are overweight to various degrees, from "genki" women who are just 10 lbs overweight to buttertrolls who wander around sci-fi cons. A better measure would be relative boob size of people with "healthy" body-mass indices.
The leg thing is something I've noticed and like quite a bit (which is probably why I favor tall women). Legs were an 80's thing here in the US. In many ways, Japan never really left that decade.

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