What not to do in Japan

um, hello. Next year, i'm going on a trip to japan, so i wonder what i shouldn't do there. because i know that japanese people are really polite ect.

There is a good starting point here:

http://www.japan-guide.com/e/e622.html

Have fun and don't worry too much, foreigners (especially tourists) get endless leeway.

I can only think of two things you should remember:
1. No tipping.
2. Try not to be loud.

Also don't eat food on urban public transport (long distance is usually fine, but make an effort for it not to be smelly food even then).

thank you so much! now i know a little more about it.

Maybe these are useful in a sense?
http://web2.airmail.net/will/japan2long.html
http://www.gadling.com/2007/09/18/big-in-japan-33-reasons-why-youve-be...

being loud and obnoxious is the #1 complaint i have against foreigners visiting japan

#2 take off your shoes if you go into a changing room in a department store or clothing shop - same goes for certain izakaya, if they have a wall of small lockers by the entrance then you have to take off your shoes before entering the place

#3 bring cash and don't expect to be able to pay by card - some places accept cards but it's still relatively rare especially in restaurants / drinking establishments or older/small shops

#4 try not to get in the way during rush hour at stations, if you're searching for your train at the ticket computer don't hog the computer while people behind you are waiting etc..