A fish grill or fish broiler is a kitchen appliance used primarily for the purpose of cooking fish and is commonly integrated into Japanese kitchen stove tops. It generally appears as a small windowed drawer around the control knobs of the stove top below the burners. It's used by pulling it open like a drawer where one can then place fish or other items to cook onto a grill, and then slide them back inside where they'll be placed under a broiler-like burner. The knob to control the fish grill is typically located with the knobs for the stove top.
Example of a fish grill in operation: post #2745382, post #5005518