[Nyororin]

He only says that he doesn`t understand them. The guy looking at the phrase book asks if he can speak English, and he pretty much answers that he doesn`t. No talk of moles.

In Japanese, "mole" (as in the animal) is モグラ (mogura). In terms of a mole in a group like that, 内通者 (naitsuusha) is probably the best approximation. Although normally you`d just call them a "spy" which is the same as English in Japanese.