Since Japanese food was recognized by UNESCO as an intangible culture heritage, we must have knowledge the manner of dining.
First is Tezara(手皿), to eat something with turning the other palm upward near your mouth in order to prevent dropping something soup or gravy. It looks like polite, but actually breach of manners.
Second, dissolving wasabi in soy source is impolite. Spices like wasabi should be directly put on the dish.
Third, lifting up bowls or plates with the other hand when you are holding chopsticks at the same time is also not good. If you want to take another plates, once you should put the chopsticks on.
Japanese cuisine has lots of manner. Even Japanese don’t care the manners so why don’t you study them in this opportunity?