Place chicken in crock pot on low heat. Combine sugar, soy sauce, vinegar, ginger, garlic, and pepper in a separate bowl. Mix and pour over the chicken.
Cook on low for 4-5 hours until chicken is tender. Remove the chicken, place it on a plate and shred it with a fork.
Take the fat out of the reserved liquid left in the crock pot by pouring it through a mesh strainer into a saucepan (or scoop out the fat with a slotted spoon).
Pour chicken over cooked rice and cover with your thickened teriyaki sauce.