Mix ground chicken, sesame oil, soy sauce, mirin, salt, black pepper, cayenne, green onions, garlic, and bread crumbs in a bowl. Chill mixture in the refrigerator for 30 minutes.

Preheat oven to 400°F (200°C) and prepare a foil-lined baking sheet by lightly greasing it.

Shape mixture into 16 meatballs and evenly space them on the baking sheet.

Bake meatballs for 15 minutes or until they reach an internal temperature of 145-150°F (63-66°C). Let cool and refrigerate if not grilling immediately.

Preheat an outdoor grill to medium heat and lightly oil the grate.

Mix ketchup, hoisin sauce, ginger, and rice vinegar in a small bowl to make the glaze.

Skewer 4 meatballs onto each skewer. Grill for about 3 minutes per side until lightly charred. Brush with glaze, sear for 30 seconds, then glaze the other side.