One of the things I love about Japan - tipping is not part of Japanese culture. Most Japanese folk work diligently for what they are paid by the hour and are not motivated by tips but genuinely want to provide you good service.
Its not as if the folks over here are paid buckets of gold either. Part time work in a restaurant fetches between
800 yen -
1200 yen-ish.
When I first came to Japan I tried to leave tips but only to have it given back to me!