The rule of thumb might be to go beyond looking to interacting and participating whenever possible. Even beyond the verbal there is a whole world of subtle interaction in terms of facial expressions, palpable emotions, gestures and favors. The unexpected extras in service, for example, can be a highlight as one appreciates the underlying desire to please. When the Japanese have free time during the day they shop, go to restaurants or coffee shops, browse in bookstores because reading is permitted, occasionally strolling in nearby parks. They are inhibited to cross group lines and meet strangers, but foreigners can be an exception, among residents who may wish to enjoy more freedom from normal restraints.
Human relations are complex and delicate in Japan.
It is said that the Japanese emphasize form while Westerners emphasize content, but on a deeper level in Japan, form virtually symbolizes social relations. The very importance of human relations has created much artifice and difficulty, a dichotomy between surface accomodation and depth of true intention, so one must be careful and sensitive, that is, considerate. The ubiquitous kissaten are much more than places to drink coffee. The price of a beverage is 2 or 3 dollars, but one is paying for the space in a land of few public comforts, for the time since people often stay nearly an hour, for the meeting place to chat with friends, for the facilities and free reading materials. First ice water, and later green tea is often served for free.