Changing money requires you to show your passport and fill-out several forms. The process can take a while if the bank is busy, and is a good introduction to Japanese bureaucracy. Newcomers will be surprised at how many people work in a bank and amazed at how many hands your little slip of paper touches before it finally gets back to you. Using travelers' checks gives you a slightly better exchange rate than cash, and is the safest way to carry money. These are easy to find in large cities but can be hard to come by in more rural areas.
Japan is an extremely safe country and most people carry large amounts of cash around all the time.
So, although you should use common sense, it's a good idea to exchange enough cash before you head out of major metropolitan areas. Credit Cards, ATM's and Wiring Money Major credit cards are accepted at large hotels, restaurants, shops and many other places, but Japan still remains a cash society. It's always best to ask first if you don't see a sign by the door or cash register, and even if you do see the sign, some places will only take locally issued credit cards. The most commonly used cards are Visa and American Express, and to a lesser extent, Master Card and Diners Club. Cash advances are possible, though it is often hard to find a bank that will do it.