Koji rice is steamed rice inoculated with Aspergillus oryzae mold, a key ingredient in Japanese fermentation that breaks down starches and proteins into sugars and amino acids, creating umami flavor. It's the base for staples like miso, soy sauce, and sake, and is used in modern cooking as a marinade (shio koji) to tenderize and flavor meats, fish, and vegetables. Dry age it in the refrigerator for 48 hours. I may report back tomorrow.