The factory makes koji spore ― Japan's "national mold" ― and supplies it to brewers of sake and makers of seasonings such as soy sauce and miso. Only around 10 koji spore makers are left in Japan.

Beni Koji has been used in Japan for centuries, primarily in producing fermented foods and beverages. The process begins with steamed red rice, which is inoculated with Monascus purpureus spores ...