[6t6t6]

I live in Japan and my wife is Japanese. Also, I had this conversation with several Japanese people.

I can tell you that most Japanese I know hate the concept of tipping and it makes them uncomfortable. They also hate giving tips. Not because of the money, but because they think that tipping is a way of looking down the other person.

Of course, when I say offensive I don't mean that they will curse and hate you forever. But probably some will think: "I already have a salary, I don't need you give me your coins".

If there's an scale of socially awkward situations, I guess tipping would be slightly under asking ketchup for your sashimi. But definitely not as bad as going into someone's house with your shoes on.