“Tell me your address and I’ll tell you… nothing at all!” In Japan, an address is not enough to go somewhere, and you’ll probably never reach your destination if you don’t bring a map with you.
I see several reasons for this. First of all, streets in Japan generally don’t have a name (except for the big avenues). 
The next problem relates to how japanese addresses are structured:
- prefecture (to-dô-fu-ken 都道府県),
- city (shi 市) or district (ku 区),
- number of neighborhood (chôme 丁目),
- block number (banchi 番地),
- house number (gô 号)
- building name and room number.
How not to find ones way when everything is so well-stuctured? The only problem is that numbers are not necessarily in sequence. Rather, they are generally completely unordered! This is true for the block number as for the house number. Better to know beforehand.
Fortunately, most shops and restaurants publish an access map on their website or in their fliers. And there are very good websites (most in Japanese, though) allowing to search area maps from an address (see for example: http://map.yahoo.co.jp/ but there are many others).