Types of Sake

There are several different types of sake, and the following special designations are specified by the Japanese government. Sake that falls outside the specially designated sake categories is typically called "futsu-shu". This includes sake made with a rice polishing ratio over 70%, made with ingredients other than the ones approved for specially designated sake, and sake containing more than 10% brewer's alcohol.
Junmai Daiginjo
Junmai daiginjo-shu is regarded as the highest-grade sake. The best products in this class deliver a good blend of refined taste with acidity and umami.
Junmai Ginjo
Because ginjo brewing techniques are used in making junmai ginjo-shu, the acidity and umami are toned down and there is a clear ginjo-ka.
Tokubetsu Junmai 
Junmai-shu and tokubetsu junmai-shu are made only from rice, koji and water, highlighting the flavor of the rice and koji more than other varieties. There are no requirements regarding polishing ratio. Junmai-shu is typically high in acidity and umami, with relatively little sweetness.
Daiginjo-shu is a form of ginjo-shu made with even more highly polished rice from which at least 50% of the outer layer of the grain has been removed. It has an even more refined taste and stronger ginjo-ka than ginjo-shu.
Ginjo-shu is made with rice grains from which more than 40% of the outer layer has been removed by milling. Fermentation occurs at lower temperatures and takes longer. Distilled alcohol equivalent to up to 10% of the weight of the polished rice may be added.It has a fruity fragrance, called ginjo-ka, with a light, that is low in acidity. “Light” does not simply mean “mild” or “diluted.” The sake should also have a smooth texture (mouth feel) and a good aftertaste.The specific characteristics of ginjo-shu vary by brewer, with the more fragrant varieties designed to highlight ginjo-ka and others designed with more emphasis on flavor and less on ginjo-ka.
Tokubetsu Hojozo | Honjozo
In honjozo-shu, the emphasis is on flavor and there is little ginjo-ka or aging‐induced aroma. It has a reasonable level of acidity and umami and rather than asserting the aroma and taste of the sake itself, it helps to bring out the taste of food.
This is a white, cloudy sake made by straining the moromi through a coarse cloth only. Nigorizake that is shipped without pasteurization is called kassei seishu (active sake), and still contains living yeast and enzymes.
A sparkling sake is a great aperitif. Usually low in alcohol with a fuller body, it can have bubbles from natural fermentation or added-carbonation just like sparkling wine.
Sake can be matured for 6 months to one year. For example Junmai-shu, longer-term storage smooths out the sake's flavor. Some koshu is aged for two, three, or even over five years.
Most sake on the market has had its alcohol content adjusted 15-16% through dilution with water, but since genshu is undiluted sake, it’s alcohol content is often quite high, at 18-20%.
The traditional method of propagating the air-borne wild lactic acid bacteria. In order to make it easier to gather wildlife lactic acid bacteria, the brewery workers use a tool called Kai to mix the mixture of steamed rice, water and Kobo. This process is called Yama-oroshi  and requires great hard work and they have to do it every 3-4 hours night and day at the room temperature of 5 degrees Celcius where lactic acid bacteria are active and germs are inertia. The Sake using this hard-working process of Yama-oroshi is called Kimoto.
In 1909, National Research Institute of Brewing developed a new method which omits the laborious process of Yama-oroshi but still produces the very similar Sake. To be specific, they just rearranged the order in which steamed rice, Koji and water are added to Shubo. The Sake using wildlife lactic acid bacteria but without Yama-oroshi process is called Yamaha.
Sake is usually made by pressing the moromi after that, sake is filtered to stabilize the quality, but this sake skips that last step.
This sake is sent to market without any pasteurization in the production process. There are many types, such as junmai nama and ginjo nama.
Freshly pressed sake is stored at low temperatures, and is pasteurized only once, just before shipping. This sake retains the flavors of unpasteurized sake.
This sake is pasteurized, stored, and moderately matured for a stable product quality. The matured sake is then bottled without a second pasteurization.