To prepare bonito flakes broth. Bring the water to a boill in a saucepan, pour in bonito flakes, kelp and ginger. Stop the heat immediately.
Filter off any foam and allow the bonito flakes to settle on the bottom of the pan. Strain the broth through a fine sieve paper towel. Remove from the heat.
Clean crab with a brush. Remove shell and inner organs. Chop off legs and cut the crab into 4 pieces.
Soak the rice in a saucepan with 1 cup of cold water overnight or at least 1 hour to get a softer and fluffier texture of rice.
Heat the saucepan, add prepared bonito flakes broth and bring to a boil. Add the crabs and reduce to low heat.
Continue to simmer until the rice break, thick and smooth. Continue to simmer until the rice break, thick and smooth.
Ladle the porridge into a bowl, garnish with coriander, spring onion and pepper before dish out.
