JAPAN: Tipping in restaurants
We might see tipping as a social norm when going out in the States, but in Japan, not only it is not customary, but it is even considered rude. With a few exceptions, you will be turned down and most probably feel awkward about the whole moment.
Japan is ruled by a sense of dignity and respect that the rest of the world doesn’t always understand, but it’s inconceivable for a worker to accept any extra money for their services other than their paychecks. If you do want to show gratitude for one’s service, put the money in an envelope, maybe that way you’ll have better chances of it being accepted.