Place chicken thighs in bottom of slow cooker.
Combine ginger, garlic, soy sauce, vinegar, Splenda/Stevia and Worcestershire sauce in a bowl. Pour over chicken.
Cook in HIGH for 2 1/2 - 3 hours (LOW for 5 1/2-6 hours) Remove chicken from slow cooker.
In small bowl, stir together water and cornstarch. Add to the teryaki sauce and stir until thickened.
Return chicken thighs to the slow cooker and stir to coat with teriyaki sauce
Sprinkle green onions and sesame seeds on top just before serving.