Japan is a country with a land mass smaller than that of California. It is situated from a point slightly north of 45° north latitude to a southern most point of 20° below north latitude. The equivalent in the USA would be from farther north than Portland, Maine to below Key West, Florida. Japan is comprised of more than 3,000 islands, making it an archipelago. Extending more than 1,500 miles from the northeast to southwest, the nation is characterized by numerous regional differences in climate, water quality, and geology as well as indigenous rice varieties. The bulk of Japan sits on five main Islands: Hokkaidō, Honshū, Shikoku, Kyūshū, and Okinawa. These Islands are further broken down into regions and prefectures, and it is these regions and prefectures that are quite commonly referred to when individuals are speaking of sake.

It is important to understand that the sake brewing industry in Japan is governed or controlled by the National Tax Agency (Kokuzeichō). The National Tax Agency, which covers all 47 prefectures, is broken up into 12 smaller departments, each of which contains a certain number of prefectures. These tax department regions mirror what the Japanese refer to as their sake regions: Hokkaidō, Tōhoku, Kantō-shinestsu, Kantō, Hokuriku, Tōkai, Kinki, Chūgoku, Shikoku, Kyūshū, and Okinawa. Please refer to the map to see which prefectures are within each region.

Sake is produced in all but one prefecture (Kagoshima). As a side note, Kagoshima Prefecture has earned its place in the beverage world as the leader in Shōchū making. As sake consists of 80% water, it is most important that a brewery be located near an excellent aquifer. Considering this, and given that it is easier to transport the rice than the water, it is no surprise that many of the most important sake-producing regions are located near some of the nation's purest water supplies: e.g. Fushimi (Kyōto Prefecture) and Nada (Hyōgo Prefecture). The sakes of each area vary in style according to a combination of the chemical makeup of the local water, the type of cultivated rice used, the traditions of the tōji (brew master), as well as regional history and culture, regional products, and local dietary habits. Nada, the largest region by volume, is known for its masculine, sturdy and dry sakes due in large part to the high mineral content of its water, while Fushimi with its softer water produces more feminine sakes that are often slightly sweet. Niigata is popularly regarded for its precise, dry, and angular sakes. Akita makes tightly wound, nervy sakes balanced by a medium mouth feel. Hiroshima, known for its soft water, creates appropriately soft sake, which is also often sweet. The region of Fukushima is large and hard to generalize about, but it tends to be responsible for some of the more blousy and flamboyant sakes on the market.

Long ago, there was a great deal of regional variation among the different sake producers. From sweet sake found in the inland hills and mountains to cleaner, linear, dryer sake found in the plains closer to the sea. Prior to the modern infrastructure that today's current public transportation system and highways provide, regional differences were more prevalent in the sake world. As Tōkyō became an important market for sake, many sake producers began to alter their recipes to suit the buyers of Tōkyō. Regional variations became diluted. Of late, though, there has been a tendency for the brewers to search for and reacquaint themselves with their regional identities. This will lead to more variation among producers and regions, and the sake drinker will surely benefit from this new found interest in reviving more traditional distinctions among the various sakes that will emerge as a result.