may be it's the same than in "Garmin Japan Road Navigator (RoadNavi) :


*You may not find places by address. Note that including full address search (i.e. geocoding), is technically impossible using the US Garmin units since Japanese banchi address is not based on the street number system like the US or Europe (the most of residential roads do not even have their name). You may search places under "Cities" category. The "Cities" category includes not only cities, but also almost all place names in Japan. For example, if you are looking for "Akasaka 3-chome", please spell "AKASAKA3."