The main ingredient in traditional Japanese sake is rice. Sake is often referred to as rice wine, but the brewing process is more similar to beer fermentation. Special types of rice, known as sake rice or "shuzō-kōtekimai," are used for brewing to achieve the desired flavor and quality. The rice is polished to remove the outer layers, affecting the final product's taste and aroma. Additionally, water, yeast, and koji mold are used in the fermentation process to convert starches into sugars and then into alcohol. The result is a diverse range of flavors and aromas in sake.