Japan values privacy more than other cultures. Cash is unlikely to disappear anytime soon. Even ordering online you can buy things by (1) place the order and get code (2) go to convenience store, tell code, pay cash. Merchant knows what you ordered but payment processor does not know who you are, only that cash was paid for order #XYZ. Similarly adult videos in hotels are paid by cash. You put cash in card dispensing machine and get code. Type code into TV.