In a small mixing bowl, combine the teriyaki sauce ingredients; soy sauce, brown sugar, pineapple juice, garlic and ginger. Whisk ingredients together until sugar dissolves.
Add chicken and teriyaki sauce to a plastic baggie, or a casserole dish. Allow to marinate, in the fridge, for at least 4 hours or overnight. Flip the chicken half-way through marinading time.
Heat a grill to medium to medium-high heat. Once preheated, remove chicken from marinade and cook on each side, for about 5-6 minutes, until the internal temperature reaches 165 degrees.
Meanwhile, add the reserved marinade to a medium saucepan over medium-high heat. Simmer the marinade for 5-10 minutes until it begins to thicken. Remove 1/2 of the marinade from the saucepan, and use one half of the marinade to baste the cooking chicken.*
Once the chicken is cooked through, add it to a baking dish and add the remaining 1/2 of warm marinade (that was NOT used to baste the chicken).
Serve and enjoy!