In an enamel pot add the chestnuts and enough water to cover them (unlisted), bring to a boil, and turn off the heat. After they have cooled, remove the outer shells without damaging the inner chestnut skins.
In an enamel pot add step 1 and enough water to cover it (unlisted), add 1/2 teaspoon baking soda and bring to a boil. Reduce to a low heat, and boil until the water turns dark red.
Rub the chestnuts from step 2 by hand, and remove whatever skin you can. Let them soak in the water for a while.
Add the chestnuts from step 3 along with enough water to cover them (unlisted) into the pot, add in 1/2 teaspoon baking soda and bring to a boil, reduce to a low heat and boil until the water turns red, and then simmer until cooked through.
Take the chestnuts from step 4 out into water, cleanly remove the sinews with a toothpick. Change the water several times to remove the bitterness. Repeat until the water runs clear. Then drain the water.
Add the chestnuts from step 5 and Japanese sake to the pot and bring to a boil, then add in the sugar. Remove any scum that surfaces and cover with a small sheet of aluminum foil that sits right on top of the chestnuts (otoshibuta). Reduce to a low heat and simmer for about 20 minutes, then let cool.
Repeat step 6 two more times. Remove the aluminum foil sheet, and let the chestnuts sit in the broth overnight to allow the flavor to soak in. If the room temperature is high, put them in the fridge.
Please check out "Superb! My Family's Simmered Chestnuts (Recipe ID: 2012676)".
Please check out "Chestnuts Simmered in Red Wine (Recipe ID: 1589527)" as well.
Please take a look at "Chestnuts Simmered in White Wine (Recipe ID: 1611578)" too.
Also check out "My Family's Recipe Tips (Recipe ID: 2373598)".
Story Behind this Recipe
I have moved on from making plain simmered chestnuts to ones made with red or white wine since last year. This year I decided to try and make them with Japanese sake.
When you want to preserve these for a short time, pour the liquid and chestnuts into a sterilized jar, and store it in the fridge. When you want to preserve them for longer, pour the liquid and chestnuts into a clean airtight container, and store in the freezer.