Where are the setting in first 39 clues book?

At first, in The 39 Clues, Book 3: The SWord Thief, Amy and Dan Cahill fly to Japan. Then, their uncle Alistair Oh, who they are working with, discovers in Japan that the clue is actually in Korea. In Korea, the clue finally turned out to be hidden in a cave in the mountains of Pukhansan National Park.