"If you don't have sky club access there are some restaurants airside including McDonalds and Japanese options. They take credit cards. Not sure how much you have traveled before, but be sure to call you credit card company and tell them you are traveling to Singapore AND Japan- otherwise Narita might be the last place you use your credit card."

A question about the quote listed above. Can you explain the reason why this would be a good idea to call my credit card companies? I have a similar trip coming up and don't want to lose credit card usage. Any help appreciated.