If you're looking for hard-to-find sake from Gunma Prefecture you'll find more than forty varieties on sale here, along with local craft beers, wines, food and handicrafts. There's a tasting counter in one corner where you can sample sake for Y500 a glass; they also serve tasting flights of local wines (three glasses for Y1000), craft beer and desserts.
In addition to booze, they stock the usual selection of locally made pickles, locally grown rice, soy and other sauces, candies and crackers, jams and juices, meats and cheeses. There are character goods featuring Gunma-chan, the prefecture's mascot, and a rack of pamphlets encouraging you to move to Gunma. Upstairs is a restaurant called Tsuru (03-3571-7763) which serves Gunma cuisine.
This book will introduce you to more than twenty of Japan's favorite specialty foods that are less well known abroad, along with a guide to the best places in Tokyo to try them and expert tips on what to order. From Bento.com.