Technically speaking, sake is a fermented alcohol beverage made from rice, water, and Koji mold. However, sake is more than that in Japan as it is indispensable to Japanese Shinto rituals. In ancient times, sake was sacred offering dedicated to the gods. 

Where does it come from ?

Sake's origin is unclear. It is considered to have begun over 2000 years ago in Jomon Period (縄文時代, Jōmon jidai 14,000–300 BC) when rice cultivation started in Japan. Now the sake is the national alcohol beverage of Japan which has been deeply related to Japanese people's daily life.

What is sake made from ?

Sake is made from fermented rice. Saka-mai (酒米), the rice cultivated to produce sake, is about 30% bigger in size and weight than normal table rice. It has a large starch in the middle which will be converted into sugar, and then sake afterward.

What is the alcohol percentage of sake ?

When sake naturally occurred,  the alcohol percentage is around 20% due to it's brewing method called 'Multiple parallel fermentation' (平行複発行: Heikoufukuhakko), which is saccharification
and fermentation are taking place at the same time in a same place.

How do you drink sake?

There was an era when people always heat up sake to disguise its low quality. Just after the WWⅡ, serious shortage of rice occured. Although the method to add distilled alcohol  was a standard practice to prevent the spoilage of sake.  To bulk it up, this method was utilized to increase the sake production.  However, the quality of sake has been so much improved over the last 70years. So you don't need to heat it up all the time. In fact, what's so unique about sake is you can enjoy at various temperature from hot to chilled.

CLASSIFICATION

Jargon Busters

Sake and Shinto Ritual - Sakazukigoto 
 Sakazuki (盃) is a small to medium-sized cup for drinking sake and "Sakazuki-goto"(盃事) is a ritual of drinking sake to purify the bories or things or sometimes exchanging those sake cups as a means of pledging royalty between newly wedded couple, or among Yakuza.

Shinto wedding 

 “Sankon-no-gi,” by which the couple take marriage vows through three sips of omiki, sacred sake.

Otoso

"Otoso' or 'toso' is a medical alcoholic drink made of natural herbs steeped in sake or Mirin which are traditionally enjoyed on New Year’s Day to flush away the previous year's maladies and to aspire to lead a long life. 

Oyako Sakazuki & Kyodai Sakazuki

Sake is used by Yakuza to solidify their friendships or bonds. "Oyako Sakazuki"Parent-Child Sake Cups are usually performed between a superior and their subordinate, to signify a parent and child relationship. ​"Kyodai Sakazuki" Brothers' Sake Cups are performed between equals, signifying a relationship like that of brothers.

Jichinsai

The ceremony, called "Jichin-sai", is a Shintoism ceremony to purify the ground where new building is going to be built. During this ceremony, a Shinto priest pour the sake to the ground and pray to a god for safe completion of house building work 

Sake in the movie - Your name

Kuchikami No Sake - According to a book titled Osumikoku Fudoki 大隅国風土記 written in the early 7C, which describes natural features, climate and products in Kagoshima prefecture, the ancient form of Sake was produced by people spitting chewed rice into a pot. Saliva contains the starch-degrading enzymes, Amylase and Diastase. These enzymes convert to sugar causing fermentation to occur by natural yeast.