We spent 3 weeks in Japan in 2006. We were told to bring a lot of cash and an ATM card that worked in Japan. We did both things (it's easy for us to buy yen and other major currencies at our bank). Wound up using very little cash. So we never had to use the ATM card.

Note that we had some reservations at bigger deal restaurants. Also poked around a lot exploring restaurants. A few inexpensive restaurants were cash only - but most restaurants took at least 1 major credit card. Michelin didn't have a guide back then. IIRC - we had a Zagat's guide. But I can't recall whether it had information about whether restaurants accepted credit cards.

So I guess this time around - if we decide to dine at an expensive restaurant that only accepts cash - we'll have to add that cash to whatever cash we might otherwise take with us. Robyn