In a mixing bowl, whisk together ketchup, brown sugar, soy sauce, pineapple juice, olive oil, rice vinegar, minced garlic, minced ginger, and sesame oil. Reserve 1/2 cup for later use.

Place chicken in a resealable bag, pour marinade over, seal tightly, and refrigerate for 1 hour.

Soak wooden skewers in water for at least 1 hour; skip for metal skewers but ensure they are clean.

Preheat grill to medium-high heat (around 400°F / 200°C).

Combine diced green peppers, diced red onion, and diced pineapple in a separate bowl, drizzle with olive oil, season with salt and pepper, and toss to coat.

Thread marinated chicken, vegetable mixture, and pineapple onto soaked skewers, alternating ingredients.

Grill skewers for 5-6 minutes, brushing with reserved marinade halfway through, then flip and grill another 5-6 minutes until chicken reaches 165°F (74°C), and vegetables are tender.

Remove from grill, let rest for a couple of minutes, then serve with rice or grilled corn.