Question about YEN & Credit Cards

I am spending 3 nights in Osaka, 2 in Kyoto and 4 in Tokyo in October. My hotels are already paid for and my Shinkansen tickets will be waiting for me at my hotel which I will pay for by credit card upon departure there. For the most part I will eat as inexpensively as possible with an occasional splurge here and there.
I am not a big shopper but may buy a few small inexpensive gifts to bring back home. How much YEN do you think I should bring with me for subway, local trains and meals. Can I assume that some of the pricier restaurants take credit cards ? Are both Visa Cards and American Express accepted in Japan ? Thank you.

Deb,

Credit cards are more widely accepted than many of the (out-of-date) guidebooks would have you believe. American Express may not be quite so widely accepted as Visa and Mastercard, though.
As for how much yen to take, a cash card that can be used at Japanese ATMs would probably save you some hassle.