Place chicken thighs into a 5–6 quart slow cooker.
In a bowl, whisk together soy sauce, honey, ketchup, garlic, ginger, sesame oil, and red pepper flakes.
Pour the sauce mixture over the chicken in the slow cooker.
Cover and cook on LOW for 3–5 hours or HIGH for 2–3 hours, until tender.
Remove chicken and shred with two forks.
In a small bowl, whisk water and cornstarch until smooth.
Stir slurry and shredded chicken into sauce in the Crock Pot.
Cook on HIGH for 15–20 minutes, or until sauce slightly thickens.
Spoon over rice, noodles, or vegetables. Garnish with sesame seeds and green onions.
