The primary ingredient used in traditional Japanese sake is rice. Specifically, sake is made from a particular type of polished rice, known as sakamai, which undergoes a fermentation process. The rice is polished to remove the outer layers, affecting the quality and flavor of the final product; the more it is polished, the higher the premium sake. Koji mold is introduced to convert the rice starch into sugars, which yeast then ferments into alcohol. Sake can vary in flavor, aroma, and alcohol content, reflecting the brewing techniques and ingredients used. It has deep cultural significance in Japan, often consumed during special ceremonies and celebrations.