Place the chicken thighs in the slow cooker.

In a separate bowl, whisk together the pineapple juice, soy sauce, brown sugar, garlic, ginger, sesame oil, and black pepper. Pour this mixture over the chicken.

Add the diced bell peppers, onion, and pineapple chunks to the slow cooker, stirring gently to combine.

Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the chicken is cooked through and tender.

Once cooked, remove the chicken from the slow cooker and shred it using two forks.

In a small bowl, mix the cornstarch and water to create a slurry. Stir this into the sauce in the slow cooker and cook on high for an additional 15-20 minutes, until the sauce thickens.

Return the shredded chicken to the slow cooker and stir to combine.

Serve over cooked rice and garnish with chopped green onions.