The follow is selection of activities that are not done in public in Japan. Although these behaviors are seen as being rude by Japanese standards you, as a foreigner, should not worry too much about adhering to them as it is not expected of you.
1) It is considered a shameful act to kiss in public.
2) Hugging is considered impolite in Japan, as is any other sort of physical contact.
3) Chewing gum: doing this in front of someone is not excepted, but smoking in front of someone is. It is also considered rude to be the only person eating something.
4) One should always take off their shoes when entering a Japanese house or restaurant (you will most often be supplied with slippers). This is one that foreigners should observe.
5) Of all of the above this may seem the strangest to foreigners: It is considered rude to look into the kitchen of a house that one is visiting.
6) This may be the most pleasant to foreigners (especially Americans): Civil court proceedings are avoided as Japanese emphasize relationships based on trust rather than contracts. Therefore most problems of a civil nature are discussed through third party mediation. The only time one goes to court is when there is no hope of maintaining a relationship between two parties. It is interesting to note that the number of lawyers in Japan is one-fiftieth of that in America.