In a medium-sized bowl, combine soy sauce, ketchup, brown sugar, honey, rice vinegar, pineapple juice, and sesame oil. Whisk until smooth.

Add minced garlic, grated ginger, and ground black pepper into the marinade, whisking until well combined.

Place chicken breasts in a shallow dish or resealable plastic bag. Pour marinade over the chicken, seal and refrigerate for at least 30 minutes, preferably 2-4 hours.

Preheat your grill or grill pan to medium-high heat, around 375°F to 400°F.

Remove chicken from marinade, allowing it to come to room temperature.

Grill chicken for about 6-7 minutes per side, until golden and cooked through (internal temperature should reach 165°F).

While chicken is grilling, pour reserved marinade into a small saucepan and simmer for about 5 minutes to thicken.

Once cooked, let the chicken rest for a few minutes, then brush with thickened marinade before serving.

Serve hot, with optional garnishes like chopped green onions or sesame seeds.