First off, there is an ample number of things that aren't rude in America, but most certainly are here. There are far too many to list, but a few are talking loudly in a train/elevator, audibly chewing gum, eating while walking, physical contact beyond being shoved in a train, not standing on one side of an escalator to let people walk, discussing money, asking for a 'doggie bag', and so many other things I can't mention. What I've found is a few things that are rude in America, but perfectly acceptable in Japan.
- Public Intoxication: Every Friday and Saturday night,this is something I often see. I don't mean someone's had a few beers and can't quite walk a straight line. I see falling down on the sidewalk, stumbling, slurring, belligerently drunk people of all ages and social classes. I've seen businessmen in suits and ties too drunk to walk and women dressed to the nines being carried by their friends home. I'm not sure if "rude" is the right term for this one, but it certainly is somewhat socially acceptable.
- Slurping Noodles: Not only is this not rude in Japan, it's actually considered rude if you DON'T slurp noodles. Slurping means you enjoy your meal. I, and other Americans I've talked to, have a hard time slurping as it's been ingrained in me that slurping = rude. I went to eat soba noodles with a Japanese friend of mine and he was slurping away and I just couldn't. He kept giving me this look of disgust, like I was the rude one. Which, in that case, I was.
- Talking with food in your mouth: I'm not exactly sure how 'not rude' this is, but I've seen/heard it enough to get the impression that it's not the worst thing in the world. As far as I'm concerned, talking with a mouth full of food is quite possibly one of the rudest things you can do. It may still be rude here, but not nearly to the caliber that it is in America.
- Lack of Eye Contact: When it's a stranger on a train, no big deal, but when you're having a nice conversation with someone, it'd be nice if they looked me in the eye. This isn't always true, but it's often. I'm personally not so great at eye contact so it doesn't bother me too much, but I've certainly noticed it.
- Asking someone's Age: This is a personal pet peeve of mine. I think age should not be a priority in how you deal with someone, so I think it's a useless question. That's not the case here. I've had people ask me right away "What's your name? Where are you from? How old are you?" I know it relates to the Sempai/Kohai culture and how they honor those older than them, so I let it slide. But, the truth is, it really does bug me.
Anyways, those are a few things I've found since getting here. As always, comments are welcome.