If you are using bamboo skewers, soak them in water for at least 10 minutes.
Pre-heat the grill to medium-high heat.
Combine the sauce ingredients in a small sauce pan. Bring the sauce to boil then reduce the heat to low. Simmer the sauce for about 20 minutes.
Cut the green onions into 1.5 inch pieces, cut chicken into bites size pieces, and remove the stems from shishito peppers.
Skewer the chicken on skewers, alternating with green onions or shishito peppers.
Place all the skewered chicken on the grill. Using a brush, baste the skewers generously with the sauce. Then turn the skewers over to cook the side with the sauce. Then baste the other side with sauce. Grill for 8-10 minutes.
Turn the skewers over. Baste the skewers lightly with any remaining sauce, as desired. Grill for 8-10 minutes.
Remove from heat. Sprinkle shichimi peppers and serve immediately.