In a small mixing bowl, whisk together the soy sauce, brown sugar, white sugar, mirin, cornstarch, water, garlic, and ginger. Set aside.

To a 4 quart or larger slow cooker, add the chicken breast and pour over the soy sauce mixture.

Cook on HIGH for 3 hours or LOW for 6 hours or until the chicken is tender and shreddable.

Remove the chicken from the slow cooker and shred using two forks. Add the chicken back into the slow cooker with the teriyaki sauce and stir.

Serve the chicken over rice and garnish with sesame seeds and green onion.