Creamy Koji sauce is a traditional Japanese white sauce. It contains various enzymes. 
The enzymes tenderize tough, fibrous textures and enhance the natural flavors on an array of foods, releasing sweetness and rich savory Umami. 
It can be used as a seasoning, marinating, tenderizer or salt substitute. 

Note: Only a small portion is actually used on foods, usually a 10:1 ratio, based on weight.