Here are a handful of breweries and importers that offer online shopping pages in English.
The selection includes a variety of seasonal packs and year-round packs.
The full line of Ezo Beer and Rogue Ales, plus several European brewers and tequila and spirits
A few ales are available from this online and mail-order health-food shop
This site lists thousands of beer offers (cases, gift sets, and individual bottles). You can browse by clicking on the beer categories. Searches are also possible but must be typed in katakana -- which can be a problem with Belgian and German names. On the Rakuten site, you need to register once with your credit card information; thereafter, you simply need to log in and do not need to re-enter information.
Similar to Rakuten Ichiba, the Yahoo! Japan Shopping site offers a smaller selection of beers. Searches may be typed in and sorted according to price.
A good selection of Japanese and world brews
A good range of Belgian, German, and U.S. brews
Six Japanese microbrews delivered to your door each month for 3,000 yen.
Wide variety of Belgian styles & others (German, UK, Irish, Dutch, Canadian, US, and various Asian beers)
Several great Japanese microbrews
Online retailer specializing in Japanese and imported microbrews
A variety of Japanese, Belgian, German, and U.S. beers
Many Belgian and German beers
A wide selection of beers from Belgium and other countries (Japan, Germany, USA, Ireland, England, and Australia)
Japanese, European, and American beers
A variety of deals on several Japanese micros
Japanese and world beers
Stocks many hard-to-find beers from several countries
Bargain hunting. Good luck!
Many Japanese craft breweries have their own retail web sites. Some work through Rakuten or Livedoor. Below are links to online shopping sites for 1) twenty-three great Japanese microbreweries and 2) dozens of other Japanese microbreweries. (Note: All sites, except Baird Beer, are in Japanese.)
Here are links to more than one hundred other Japanese microbreweries. Can't find your favorite? Try a search on Google, RateBeer.com, or beeradvocate.com.