Marinate the chicken: Rub the chicken thighs with salt koji and marinate for at least 30 minutes (up to overnight in the fridge).
Prepare the vegetables: Cut the carrot into sticks, lightly cut a cross into the skin of the eggplant, and slice the okra lengthwise.
Cook: Heat oil in a large pan over medium heat. Add the marinated chicken skin-side down and arrange the vegetables around it. Cook until chicken is golden brown (about 1–2 minutes).
Flip the chicken and vegetables. Cook the second side until browned. Then cover with a lid and reduce to low heat. Cook another 5–10 minutes until the chicken is cooked through.
Plate and serve hot with steamed rice or as a main protein in a bento-style meal.