Combine 1 cup sake, 1 cup mirin, ¼ cup sugar, and 1 cup soy sauce in a small sauce pan and bring it to a boil. Once boiling, turn off the heat and set aside.
Prepare sukiyaki ingredients. Cut napa cabbage into 2” (5 cm) wide then cut in half right at the middle of the white part.
Discard the shiitake stem and decorate the top of shiitake if you like..
Place some of sliced beef to sear and sprinkle 1 Tbsp. brown sugar. Flip and cook the meat.
Pour 1 cup of Sukiyaki Sauce and ⅓ cup dashi (or water) in the pot.
Put the lid on and bring to a boil. Once boiling, turn the heat and simmer until the ingredients are cooked through