In my opinion, that is miso-soup. Miso-soup is one of the authentic Japanese home cooking. Miso is made from soya. Fermented soybean. The easiest way of cooking miso-soup is just putting ingredients in boiled water. Cut vegetables, mash rooms, sea weeds and Tofu are suitable for ingredients. After they are cooked, adding ready made miso. Ready made miso already contained fish stock in it. Miso-soup is low calories, high nutritious.