Spray slow cooker with cooking spray and add the chicken breasts to the bottom. In a small mixing bowl combine soy sauce, sugar, lemon juice, Worcestershire sauce, ginger, red pepper flakes, minced garlic and pepper. Pour sauce over the chicken.
Cook in slow cooker on low for 4-6 hours or high 3-4 hours. Once done cooking, remove chicken from slow cooker and shred.
To thicken the sauce up, pour into a saucepan and bring to a boil on medium high until it starts to thicken up. Add tablespoon of cornstarch if needed.
Serve over rice and top with glaze. Garnish with sesame seeds and green onions if desired.