My life experience supports that: I have lived in NYC and Las Vegas and both attract a fair share of Japanese folks. Younger Japanese women are fairly goofy: they tend to get very nervous (and even giggly) when in an elevator with a man, for example. It's kind of an exaggerated nervous girlishness, I think.
Then again, maybe it's just personal to me - just my experience! :-)
We have had numerous japanese students stay with us during summer months. ALL the girls are that way. They are kept quite innocent and tend to act like little grammar school children.
Just cultural. However, they all write english. speak very little, at least from what I have seen.
Most male counterparts smoke and hang with their buddies.
Don't be deceived...it's an act many put on,esp. when around white males.