Soak the wooden skewers in water for 30 minutes prior to use.
In a small saucepan, whisk together the soy sauce, mirin, miso, sake, ground sesame seeds, and sugar.
Place the saucepan over medium low heat and cook, whisking often, until thickened.
Remove from heat and pour 1/3rd of the mixture into a separate bowl and set aside with a clean pastry brush. This bowl of glaze and brush will be for the final coating over the cooked chicken skewers. Take care not to contaminate. It should only touch fully cooked chicken.
Cut the chicken into 1 inch (2.5 centimeter) pieces.
Arrange the chicken on the skewers.
Preheat an indoor or outdoor grill and lightly grease with oil.
Add the skewers of chicken to the heated grill, taking care not to overcrowd, and brush with the glaze from the saucepan.
Cook until golden, then turn and brush again with the miso glaze. Continue to cook until the chicken is heated through to 165˚F (74˚C).
Repeat with remaining skewers.
Brush the cooked chicken skewers with the clean brush and bowl of miso glaze.
Serve immediately, sprinkling a little shichimi togarashi if desired.