Bring a MasterCard or Visa
For most Europeans bringing your usual Maestro Bank card is enough to get around.
But remember that this is not the case in Japan.
Normally 7-Eleven accepted Maestro Cards but On April 19, 2013, ATMs of 7-eleven started rejecting these cards (same for mastercards at that time, that has already been altered) which meant that if you have no MasterCard/Visa (like 3 of my friends when this happened) then you’ll be on the streets in no time.
So folks, remember to apply for a MasterCard in your country and double check when leaving.