Zōsui

Zōsui, or ojiya, is a mild and thin Japanese rice soup akin to a rice-based vegetable soup. It is made from pre-cooked rice and dashi or water seasoned with either soy sauce or miso and cooked with other ingredients such as meat, seafood, mushrooms, and vegetables. It is generally served to those who are sick or otherwise feeling unwell, and is usually only served in the winter.

Leftover soup from nabe is often re-used for zosui. Instead of rice, udon and ramen noodles are recent alternatives.