Sometimes what one country think is rude, the other doesn't. My Japanese teacher told my Japanese class that it's considered rude to ask how old someone is in Japan. I wonder.
Maybe I learned it from Japanesepod101.com or another source, I don't really remember, but I also heard that it's rude to stare at Japanese people when you're talking to them. Although, I think that's common sense but I've had conversations where we'd just give each other our full attention without looking away and not be offended by that.
Are there any other differences someone like me (like me as in I am considering living in Japan) should know about?
I know it's rude to talk on the phone in the train. Is it rude to eat? I've seen a couple Japanese people eating snacks on the train but it seems uncommon.