Prepare the Marinade: In a medium bowl, whisk together the soy sauce, brown sugar, minced garlic, grated ginger, rice vinegar, and sesame oil until the brown sugar dissolves completely.

Marinate the Chicken: Cut the chicken breast into 1-inch cubes and place them in the bowl with the marinade. Make sure each piece is coated well. Cover and refrigerate for at least 30 minutes.

Prepare the Pineapple and Skewers: Cut the fresh pineapple into 1-inch chunks. Soak bamboo skewers in water for 30 minutes to prevent burning.

Assemble the Skewers: Alternate threading chicken pieces and pineapple chunks onto the soaked skewers, aiming for about three pieces of chicken and two pineapple chunks per skewer.

Preheat the Grill: Preheat your grill to medium-high heat, around 400°F (205°C).

Grill the Skewers: Place the skewers on the grill and cook for 6-7 minutes per side, brushing with reserved marinade.

Let Them Rest: Remove the skewers from the grill and let them rest for a few minutes.

Garnish and Serve: Sprinkle the skewers with chopped green onions and toasted sesame seeds before serving.