Sushi Etiquette and Culture
The etiquette for sushi restaurants is similar to other Japanese restaurants. Japanese manners and etiquette, as in most cultures, are situational. There are things you may do in an informal setting that wouldn't be appropriate in a more formal setting such as a high quality restaurant. Manners often defy reasonable explanation and are cultural habits and norms that the majority follow.
For example; it is not only acceptable to slurp in Japan, but it is commonly done with soups or hot beverages. In America slurping is not acceptable and is considered bad manners. The reason that slurping is acceptable in Japan is because liquids served there are much hotter than served in America. In Japan slurping is done to help cool the very hot liquid.
Culture is constantly changing - what one generation finds objectionable another may embrace. If you are with someone knowledgeable about the manners and customs ask them and they will be delighted to explain.
Many customs have logical reasons or historical basis but others do not.
The proper way to eat nigiri sushi is to dip just the topping into the soy sauce and eat in one bite. It is acceptable to pick nigiri sushi up with your fingers. The reason you shouldn't dip the rice into the soy sauce is that it will soak up too much sauce and overpower the light flavor of the fish and rice. If your chef has already brushed a sauce on your nigiri sushi you shouldn't add any.
Sushi dining is often a group experience. In Japan you should always fill other's glasses, whether sake or beer, never letting your friend's glass get empty. This may lead to drinking more than you would like. Just go slow and enjoy.
Soups are served very hot. Japanese bowls have a ridge on the bottom that serves the same purpose as a handle on coffee or tea cups. Rest the ridge on your fingers so that you don't burn them. Since the soup will be very hot it is OK to slurp lightly to cool the soup as it goes into your mouth. Spoons are not used for soup in sushi restaurants.
If you are sitting at the sushi bar it is expected that you will order any sushi items from the chef. However, soup, beer, or other non sushi items should be ordered from the waiter/waitress. In order to get their attention you may say "sumimasen".
In Japan the tip is included as part of the service charge. In America you should tip as you would for any restaurant.
Begin your drinking with a 'kampai' and your meal by saying itadakimasu （いただきます）.
Japanese have a set of manners or cultural norms associated with chopsticks. An easy one to learn is that you shouldn't rub your chop sticks together or otherwise polish them. Doing this implies that they are of inferior quality. Other chop stick rules may be based on how the dead are treated, on hygiene, or tradition.
Sticking chop sticks into rice is something that is done when leaving rice as an offering at a grave. For this reason it is considered bad manners to stick them in your rice.
Other cultural rules regarding chopsticks: Place them, parallel not crossed, on the chopstick rest called hashi oki （箸置き） when not using them. Do not pass food from one set of chopsticks to another. Don't stab your food. Don't lick, suck, or leave them in your mouth. Don't move plates or other dishes with them. Don't take food from a common plate with them. Don't use them as pointers or toys.
Yes, there are many rules and you can learn just a few or improve your cultural knowledge by learning more.