Crockpot Hawaiian Chicken

4 boneless, skinless chicken breasts, cut into chunks
1 c. pineapple juice, from canned pineapple
1/4 c. brown sugar, firmly packed
12 oz. can pineapple chunks, drained
chopped onion, optional
1/2 c. green pepper, chopped

Combine all ingredients. Place in lined crockpot. Cook on low for 6 hours. Serve over rice with Katsu or soy sauce if desired.