Shio Koji (塩麹) is Salty Koji seasoning that can be used to season various food and marinate meat. Koji is white rice with edible fungus, and it is used to ferment food such as Miso and Soy Sauce.  When Koji is fermented with salt and water, it develops a salty but mellow flavor with a touch of sweetness.  Originally Shio Koji was a very old traditional seasoning in Japan, and hadn’t gotten much attention for a long time until about a decade ago.  Somehow it was picked up in the 2010s again, and it became a mainstream seasoning for many modern Japanese dishes.