If there's one other aspect of Japanese culture that stuck out to me, it was a heavy reliance on cash.
In the US, I use debit and credit cards for almost every purchase besides visiting a hole-in-the-wall cash-only restaurants. In Tokyo, not even the train stations accepted credit cards to purchase subway tickets. Major chains took credit cards, but lots of stores did not.
The practical effect of this is that you are always carrying around a considerable amount of cash, and not just paper bills, but coins. Coins in Japan come in high denominations like 50 yen, 100 yen and 500 yen ($1 = 112 yen). By the end of my trip, I had fashioned a makeshift coin purse to corral the money weighing down my pockets.
As I discovered, dropping a single coin into a vending machine for a drink was a convenient and useful way to get rid of the change jangling around in my pocket.