Yakitori Glaze

In a saucepan, combine soy sauce, mirin, sake, and brown sugar. Optionally add chicken skin for extra richness. Bring to a boil over medium heat, then lower the heat and simmer for about 10-15 minutes until slightly thickened. Remove chicken skin if used and strain the sauce for a smooth consistency. Let the glaze cool before using to baste grilled chicken skewers during cooking. Store any leftover glaze in the refrigerator.