Kōji

Kōji (麹 or こうじ) is a fermented food.
A mold called Aspergillus oryzae is added to rice, barley, or soy beans. This mold turns starch into sugar. Kōji is an ingredient in making many Japanese foods and drinks such as: sake, mirin, miso, vinegar, pickles, soy sauce, shōchū, and awamori.