1 pound Kabocha squash, seeded
2 cups dashi or water
1 tablespoon sake
1 tablespoon soy sauce
1 tablespoon sugar (or less, to taste. This will be based on how sweet the squash is and how sweet you like this dish)
Use a swivel peeler to remove the skin, but leave some stripes and patches of the rind on the squash. Cut it into 1-inch chunks. Use the peeler to run along the edges and cut a bevel to prevent them from breaking up during cooking.
Place the squash skin side down in a pot large enough to hold the pieces in a single layer. Add enough dashi or water to just cover the squash, and place a lid from a smaller pan (1 or 2 inches smaller) on top of the Kabocha. Bring the liquid to a boil, then turn the heat down to a steady light simmer.
Check after 4 minutes with a toothpick or a knife. There should still be a bit of resistance. Lift the lid, and add the sake, and sugar. Swirl the pan to stir the new ingredients around. Carefully turn the pieces of squash over so they are skin up now. Put the lid back on and simmer for 2-3 minutes. Check again for tenderness, this time checking that the skin is readily pierced.
Add the soy sauce. Simmer 2 minutes more. (If you like a stronger soy flavor, add the soy when the sugar and sake get added. This method just makes for a subtler dish where the squash flavor comes through.)
Transfer to a dish or individual bowls. Strain the liquid in the pan for bits and chunks of squash, then return the liquid to the pan and reduce the sauce to a thin syrup. Pour over the squash and serve hot or at room temperature.