Cut away any excess fat from the chicken and cut each piece into about a 100 g cut. Use the tip of the knife to insert several cuts into the skin to help it cook better.
Add the soy sauce, mirin, and sake to a bowl. Marinate the chicken for 30 minutes, occasionally turning over.
Heat some oil in a frying pan and start cooking the chicken with the skin facing down. Cook for 4 minutes between low to medium heat. Turn over and cook for another 3 minutes.
Wipe away the oil in the frying pan with a paper towel and add the remaining sauce from Step 2. Once it starts bubbling, lid and steam for 7 minutes over low heat.
Remove the lid and set heat to high. Place the chicken skin side down again and bring to a simmer while coating with the sauce. Once it's got a glaze to it, it's complete.
In Step 5, if you over-boil it it'll become too salty, so once it's glazed, turn off the heat.
Story Behind this Recipe
This was made using the chicken thighs I had stored in the freezer. If you use sugar you'll have even softer meat, but I make it with just mirin to keep it from getting too sweet.
After steaming the chicken with the lid, by cooking it over high heat with the sauce, you get it softened and glazed perfectly. If you're making this for a lunch box, marinade in the sauce the night before (reduce the amount of soy sauce in this case).