Cut chicken into small pieces, salt and pepper the chicken. Make sure not to over salt the chicken because tamari sauce already has a certain saltiness in them.
Turn on the stove to medium heat, put oil on frying pan, and cook the chicken. Don’t forget to sear both sides.
After the chicken in half cooked, add ginger, sake, mirin, sugar, tamari sauce, and water. Stir well until everything is incorporated.
Close the frying pan with a lid, turn the heat down, and simmer chicken for about 7-10 minutes.
Open the lid, turn the heat up, stir and simmer until the liquid is reduced.