ATM’s to withdraw money for foreigners are slightly limited on the Yaeyama islands. It’s probably wise to carry enough cash to spend a couple of days.
Credit cards are widely used in Japan. In shops, supermarkets, gas stations and restaurants in and around Ishigaki city and tourist areas, hotels it can be cheaper and easier to pay by credit card. Make sure to check this with your credit card company before your trip starts. The same as with withdrawing money from the ATM, in villages and smaller islands using your credit card can be quit difficult sometimes.
At post offices, some supermarkets (AEON such as MaxValu), banks and Familymart you can find ATM’s. Especially for post offices, plan your withdrawal during office hours. Withdrawing money at a supermarket, bank or Familymart depends on your credit card company, Maestro, Visa or Mastercard. If you’re planning to visit other islands, it’s recommended to withdraw some money in Ishigaki.
The ATM’s have an English interface, which you can choose at the beginning of your withdrawal.