This is a vegetarian Tsuyu, aka instant soup base. You use this to make broths for Japanese noodle soups (udon, soba) or dipping sauces for tempura, soba, and somen. You can definitely make this type of broth from scratch, but this is made by Ninben, the venerated katsuobushi company, so not only is it instant, it's also delicious. This is made with shiitake mushrooms, konbu kelp seaweed, and traditionally brewed soy sauce. To use, you just dilute it with water. More water for broths, less water for dipping sauces. You can also use splashes as a seasoning to add a little depth to veggies, sauces, and soups, like shiro dashi. It's concentrated, so a little splash goes a long way (and season with salt after you add the tsuyu, not before). 

Directions
Hot Noodle Soup (udon, soba): Mix 1 part tsuyu with 7 parts water and gently heat. (1 oz tsuyu + 7 oz water = 1 cup)
Dipping Sauce: Mix 1 part tsuyu with 2 parts room temp water.

1L

Vegan. Contains soy and wheat.
Refrigerate after opening.

The ingredients are clean and simple: Water, soy sauce (contains wheat), kelp, shiitake mushrooms, sugar, salt, yeast, and lactic acid.