It is acceptable to eat sushi with one's fingers,rather than chopsticks,if the dining situation is relatively casual (this also applies to dining out at kaitenzushi restaurant).
Never place chopsticks stuck vertically into a bowl of food,as this is the traditional presentation form for an offering to one's ancestors.
Accepted practice in helping oneself to a communal dish such as a salad,is to reverse the chopsticks.However this is regarded in an all male,or casual situation,as too formal and additionally,a female habit.
Women should cup their hand beneath their serving when using chopsticks when conveying food from dish/bowl to mouth.Men should not do this.
In communal dining or drinking,the youngest person present should pour alcohol for the other members of the party,serving the most senior person first.The server should not pour their own drink,rather they should place the bottle of sake,beer,wine or spirits,back on the table or bar,and wait to be served by a senior.
One should always clean one's hands before dining with the hot steamed towel provided.
Japanese soup is eaten holding the bowl to one's mouth,never with a spoon.The exceptions to this are o-zoni,the traditional soup served on New Year's Day; soups with noodles are served in larger bowls,such as ramen,are acceptable to eat using chopsticks,although the soup itself is still consumed from bowl to mouth.
It is perfectly acceptable to make a slurping noise when eating hot noodles such as udon,ramen or soba.This is standard behaviour in Japan,and Japanese maintain that inhaling air when eating hot noodles improves the flavor.
When taking a break from eating during a meal,one should place one's chopsticks on the chopstick rest (hashi-oki) provided.A hashi-oki is usually a ceramic rectangle about 4 centimeters long,or in some restaurants,a halved wine cork is provided.
Unlike Korean table manners,it is acceptable to cradle one's rice bowl in one hand when eating.
One should not gesture using chopsticks.