The main ingredient in traditional Japanese sake is rice. Specific varieties of rice are used, typically with higher starch content than regular eating rice, to enhance fermentation. The rice undergoes a meticulous brewing process that includes steps like washing, soaking, steaming, and fermentation with the help of koji mold and yeast. This process converts the starches in the rice into sugars and then into alcohol, resulting in the final beverage. Sake can vary in flavor, aroma, and quality depending on the type of rice used and the brewing techniques employed by the sake maker.