Please refrain from tipping either in a taxi or at a restaurant. Tipping is considered rude and gauche. The Japanese take pride in their professions; tipping is perceived as paying them extra to do their job.
Bathtubs are for soaking, not for washing. One usually washes oneself in the shower, then one soaks in the bathtub. Please refrain from using bubble baths or liquid soap while soaking in the bathtub.
It is common in Japan to bow instead of shaking hands. Bowing has nothing to do with worship; it's a show of respect. One usually bows to a congruent depth of the bower.
Business card exchange - when introducing oneself to a potential business client, please have business cards on your person. Upon introducing oneself, state your name and hand the card to the recipient. He or she will receive your card, read it to confirm the information written on the card, and place the card in his or her jacket pocket. When it's your turn and you are receiving the card, please perform the same tasks in like manner. Do not place the card in your back pocket; this is considered rude, as if you are sitting on the person's identity.
Respect and hospitality are two important qualities in the Japanese culture. As such, the Japanese have a difficult time refusing any request. They will hint around the request until the speaker figures out that the request will not be granted. This is usually the case when attempting to substitute set meals or other set accommodations.
The Japanese language is very soft spoken. Any raising of the voice or any big hand/body gestures is usually interpreted as anger or hostility. The Japanese may not speak English fluently; however, they are able to read it. So, writing instructions in basic English helps to facilitate communication, and speaking in soft tones greatly assist.