Sandy is going to Japan and is taking her Samsung Galaxy S5 through Verizon. How can she use data while overseas? Leo says that Verizon is the least friendly overseas. Verizon offers an international data package, but it's very expensive and complicated. She can buy the best she can, but use Wi-Fi whenever she can. Turn off international data roaming in the settings. Then Google can pre-cache her maps so she can use them there.
Another idea is to use a MiFi data card in Japan. She'll pay a fee for local data, and that could be the best option. She should check out prepaidwithdata.wikia.com to see what carriers are out there and at what price. Chances are she can get it right at the airport.