Take a large piece of dashi kombu and place in a pot with water required for amount of rice to be cooked. Add a dash of soy sauce and mirin, and add some katsuo hondashi (bonito flakes) if you require a "bolder" flavor. Gently simmer (do not let boil!) for 15-20 minutes, check for flavor. Remove kombu from stock and let settle.
Take small fillets of snapper (or any white fish with a firm texture). Slice diagonally cross the fillets about half way through the meat, and push in your favourite fresh or pickled capers. One to two capers per small fillet.
Cut the kombu into slices. Roll the fish fillets with kombu on the outside and secure with short skewer or toothpick. Place the rice in the rice cooker, and then place the rolled fish fillets on top. Fill the rice cooker to the required level with the dashi stock you have created above, and cook for the required time. The kombu flavor will infuse into the fish with the capers when cooked.