In a medium bowl combine the pineapple juice, soy sauce, brown sugar, ketchup, fresh ginger, and garlic cloves and whisk until well combined. Measure ½ cup and place in a small bowl and refrigerate for later.

Place chicken breasts and the marinade from the medium bowl into a plastic bag. Remove the air and seal the bag. Massage the chicken with the marinade then place in the refrigerator and marinate for at least an hour or overnight.

Preheat the grill over medium-high heat. Add the chicken to the preheated grill and discard marinade in the bag. Baste with reserved marinade from the small bowl. Cook for 6 minutes per side or until the internal temperature reaches 165 degrees. Serve immediately and garnish with green onion.