Reddit reviews Lonely Planet Japanese Phrasebook & Dictionary (Phrasebooks)

Write down the English words for every object around you that you regularly encounter, then put their Japanese equivalents into a vocabulary deck. Then lookup the names of places and stations around the area you're going to and add them as well so that you won't have a problem reading the signs. Genki I and II should have taught you basic enough sentence constructs that you can use along with your newfound day-to-day vocabulary to survive.

If you still really feel you're not up to it, just pickup a phrase book.