Place the kelp and water into a soup pot over medium heat. Just before it boils, take out the kelp (which can be cut up and added to the oden) and add the bonito shavings. Boil for a minute or two, then strain. Return the stock to a clean soup pot. Add the remaining stock ingredients, adding salt little by little until the flavor is to your liking. Keep the pot simmering.
To make fukuro, carefully stuff each pocket with either shirataki, pounded rice cake, or a shelled raw egg. Tie each pocket up with a dried gourd strip.
To make oden, place all the ingredients into the simmering prepared stock and cook for at least one hour. Bring the pot to the table and serve communally. Place a selection of the cooked ingredients in shallow bowls, serving the fiery mustard separately. If refrigerated, oden will be even tastier the second day. Reheat, adding more ingredients if desired, and serve.