Open up your web browser and go to http://www.yellowpage-jp.com/modules/mxdirectory/. This is the Japan Yellow Pages directory.
Look on the right side of the search bar, and choose which prefecture (the equivalent to states in the US) in which you want to search.
Type in the name of the business or the type of business you want to search for and then press the "Search" button. If you aren't sure what type of categories to search for, you can always choose one of the categories that are listed below the search bar on the site. Just click on the category you want and it will take you to businesses listed under that category that are in your selected prefecture.
Go to http://english.itp.ne.jp/index.html to open up Japan Telephone Directory - iTownpage. This works in pretty much the same way as Japan Yellow Pages.
Type in the name of the business or business category you want to search, as well as what prefecture in which you are looking. Press the "Search" button at the bottom of the search box.
Click on the "Browse" buttons in the search box if you are unsure of what prefecture (called "Region" on this site) or category under which you want to search. There will be a list of either categories or regions below the search box, depending on what browse button you click on. Click the category or region that you want. That will fill it into the search box for you. When finished, hit the "Search" button.
Go to http://phonebook.yahoo.co.jp/ to get to Yahoo! Japan Phone Book. The text will be in Japanese, but if you are using Google Chrome as your web browser, it will automatically translate the text into English or whatever language you chose. If Google Translator isn't already installed on your Google Chrome web browser, you can get it at the link below.
Type in the name or category of the business you want to search in the search bar and press the "Search" button. This will give you a listing from all over Japan.
Narrow down your search by going back to the homepage and clicking on what prefecture (called "State" on this site) you want to search in, and then narrowing the search down by clicking on the specific city, village, or city ward within that prefecture. After that, it will take you to list of all the categories you can search under. Click on your category and any sub-category to get a more accurate list of what you are looking for.