The oshibori is a warm or cold wet towel to cleanse your hands. Men will sometimes wipe their faces with it.
Japanese restaurants do not have napkins. Women often place a handkerchief in their lap. Always carry a handkerchief.
More formal meals are served on lacquer trays. Placement of dishes is significant - don't move them around on the try.
Most good restaurants place chopsticks on a rest - hashioki.
The rice bowl is to the left, the soup is to the right. Always pick up these bowls when eating.
If there is a lid, remove it and place it upside down on the tray Lids on soup can be hard to remove. Gently squeeze the bowl and remove the lid. When finished place covers back on bowls.
When there are various dishes on the try, do not finish one and then move to the next. Eat small amounts out of each one. The Japanese custom of serving things in separate dishes emphasizes the importance placed on presentation.
When uncertain about something, such as how to eat a certain Japanese delicacy, you may ask questions. This shows you are genuinely interested in learning about the culture. However, do not turn the evening into a game of "twenty questions" with your host or server.