The first time I went to Australia it took me maybe 30 minutes to adjust; then a couple little slip ups through the couple months I was there. Driving in Japan can be... interesting... it's nothing really tedious, it has to do with the signage more than the driving on the "wrong" side of the road. People are very courteous drivers there, imo. Nothing really crazy like France, Italy or the Bay Area so you should be fine if you just pay attention... at least at first.