People don’t tip in Japan. Tipping can be seen as insulting. Tipping is considered rude – and can even be seen as an degrading. Tipping will often cause confusion, and many people will chase after you to give you back your money. Overall, tipping in Japan is not customary. Respect and politeness is expected at all times, and if your tip is refused, don’t be offended.
On the rare occasion that you actually need to give a tip in Japan, do so by putting the money inside of a tasteful, decorative envelope and seal it. The tip should be presented as more of a gift than simply additional cash or payment for services. Hand it to the recipient using both hands and with a slight bow.
Source: http://goasia.about.com/od/Customs-and-Traditions/qt/Tipping-in-Japan.htm, http://www.businessinsider.in/11-Japanese-customs-that-are-shocking-to-foreign-travelers/articleshow/46292172.cms