Momiji oroshi directly translates to grated maple, but only refers to the color of the maple leaf during autumn.
Momiji oroshi is grated daikon radish and red chili peppers. It is not too spicy, since the flavors of the chili are diluted with the watery daikon radish.
The capsaicin in the red chili stimulate the palate and make it easier to taste the fragile aromas of the white fishes. Only small amounts are used since the palate will become numb if too much red chili is consumes.