Combine 1/4 cup brown sugar, 2 tablespoons soy sauce , ginger, garlic, and cayenne pepper in a bowl or zipper bag; add chicken and toss to coat.
Place in a slow cooker and cook on low for about 4 hours or until done.
When done place chicken in a broiler proof dish and preheat the broiler.
Combine remaining 1/2 cup brown sugar, water, and tomato paste, and remaining soy sauce.
Brush on chicken and cook under the broiler for about 5 minutes or until chicken is slightly crisp. Keep a close watch on the chicken under the broiler.