Koji has a long history, having been introduced to Japan via China since before the Common Era, and records show it was used in sake brewing in Japan during the Nara period. Seed koji technology was established during the Muromachi period, and in the Edo period, amazake (sweet rice drink) became popular as a summer fatigue-preventing beverage for ordinary people. In 2006, it was designated the “national fungus” by the Brewing Society of Japan, and it continues to support the foundation of miso, soy sauce, and sake brewing today.