Make the Yakitori Sauce

1. In a small saucepan, combine the soy sauce, sugar, grape juice, lemon juice, garlic, and grated ginger.
2. Cook over medium-high heat for 3 to 4 minutes.
3. In a small bowl, mix the water and cornstarch.
4. Stir the cornstarch mixture into the soy sauce mixture.
5. Cook until thickened, stirring constantly.
6. Strain the sauce through a fine sieve.

Make the Teriyaki Sauce

1. Combine the grape juice, brown sugar, soy sauce, garlic, and ginger in a medium saucepan and set over medium heat.
2. In a small bowl, whisk the cornstarch with 1/4 cup cold water until dissolved, then add it to the saucepan.
3. Heat until the sauce thickens to your desired consistency. If it becomes too thick, add more water to thin it out.

Prepare the Skewers

1. Remove the skin, debone the chicken, and cut it into large pieces.
2. Blend the chicken with the garlic in a food processor.
3. Add the egg yolk, yakitori sauce, and finally the ginger.
4. Blend everything.
5. Add the cornstarch to the mixture and mix well.
6. Shape small or medium meatballs (depending on your preference).
7. Heat oil in a pan and cook the meatballs until nicely golden.
8. Thread them onto skewers (3 to 4 meatballs per skewer) and generously coat with the teriyaki sauce made earlier.
9. Serve with white rice and enjoy hot.