There were language centers in my town, and had really affordable classes. But, Japanese was a predominant minority, so that might not be the norm where you are at. If you're going for longer than a week, you'll pick up a lot more by just listening and interacting, like Jabberwakki said. Just worry about the basics, figure out basic question forms, hi/bye/thanks, and where is the bathroom. In my experience, those are the only things (women: add 'How much') you need to know before travel. Every thing else is just pointing and smiling.