Tipping in Japan can be very confusing for everyone on their first visit. Tipping is not customary in Japan, in fact it can be considered quite rude to some. When traveling around you will find very very few instances of a tip being given, in fact you might never see it. The service industry is a highly respected industry and the Japanese are doing their best as if it was any other job.
Taxis: Never, taxi drivers treat their profession as high importance and a tip is never expected.
Hotels: Never, staff will be trained to politely refuse tip if offered.
Restaurants: Never, waiters and waitresses provide they best service they can and that’s what they are trained to do.
Bars: Never, however change bins have been seen in some of the bars or clubs in more touristy areas. It is still not expected though.
Other: It is common to leave a small tip (~1000 Yen) if you are staying in a high class Ryokan. If you do, please place this money in an envelope when handing it to the staff. Money right out of the pocket is considered rude.