Prepare the chicken thighs and place them in the slow cooker.
In a bowl, combine teriyaki sauce, rice vinegar, sesame oil, garlic, and ginger.
Pour the teriyaki mixture over the chicken, ensuring it's evenly coated.
Cover the slow cooker and cook on low for 6 to 8 hours or high for 3 to 4 hours.
Once cooked, carefully remove the chicken and set it aside.
Mix cornstarch with a little water to create a slurry, then stir it into the remaining sauce in the slow cooker.
Return the chicken to the slow cooker and stir to coat with the thickened sauce.
Garnish with sliced green onions before serving over rice or noodles.