What is the name of the sauce made from soy sauce and mirin often brushed on eel sushi?

The sauce made from soy sauce and mirin that is often brushed on eel sushi is kabayaki sauce. It is also commonly called unagi sauce, eel sauce, or unagi no tare.

Kabayaki sauce is a sweet-savory glaze traditionally used with kabayaki, a preparation in which eel is filleted, skewered, grilled, and repeatedly basted. Recipes often add sugar or sake, and the sauce is reduced until it becomes glossy and slightly thick. Its saltiness comes mainly from soy sauce, while mirin contributes sweetness and a rounded rice-wine flavor.

The name can cause confusion because kabayaki technically describes the grilled-eel preparation, not only the sauce. Tare is the broader Japanese word for a dipping or glazing sauce, so the same eel glaze may be labeled tare on Japanese menus. It is different from ponzu, which is citrusy, and from miso-based sauces. Teriyaki is related in style but is a broader sauce category rather than the most specific name for eel glaze.