Things to Avoid in Japanese Dining Etiquette
Don't blow your nose at the table; instead, excuse yourself and go to the toilet or outside. Sniffling at the table to avoid blowing your nose is actually acceptable.
Do not point at people with chopsticks or your finger while making a point.
Although you should bring a gift if invited to someone's home for dinner, avoid giving anything in sets of four or nine. The two numbers sound similar to the words for death and suffering and are regarded with superstition.