What creates stress? Asking merchants or carrying cash? If you worry about the latter, you shouldn't. It is really safe here by world's standards.
Even though plastic is accepted in a lot of places, you have to remember that Japan is more of a CASH society.
As for supermarkets accepting cards, gnaget gave you a good list of those that do.
Last edited by MichaelJapan; Oct 10, 2014 at 11:33 pm