Koji is a traditional Japanese fermentation starter made from steamed rice, koji mold, and water. It is primarily used in the production of various fermented foods and beverages, such as sake, miso, and soy sauce. The mold, known as Aspergillus oryzae, breaks down the starches in the rice into sugars, which are essential for fermentation. The process of making koji involves inoculating steamed rice with the koji mold and allowing it to ferment in a warm, humid environment for about 48 hours. This cultivation process is crucial, as it enhances the flavor and nutritional value of the final products. Koji is a key ingredient in Japanese cuisine and plays a significant role in traditional food preservation methods.