1. Driving in Japan is a lot different. Only the main roads have street names, so most of the navigation has to be done by memory. Also, Japanese always back into parking spaces rather than pulling into them. They consider it safer to do it this way.
2. If you are eating with chopsticks, it is very rude to stick them into the bowl straight up. This is only done at funerals. Instead, just lay them on top of the bowl.
3. If someone offers you a gift or a favor, you should politely refuse it. When they offer it again, refuse it again. If it is offered a third time, then you may take it.
4. The number 4 is the cause of fear and suspicion in Japan. Quite often, stores won't even build a fourth floor or sell things in fours.
5. At 5:30 (unless it is in the Winter when it becomes 4:30), every elementary school plays a tune that can be heard across the whole area that alerts all kids, wherever they are, that they need to go home now. So instead of the parents giving the kids a time to return, the tune that plays loudly from their schools tell them whether or not they are at the school.
I hope that has been at least vaguely interesting for you all! If you would like to hear more random facts, let me know.