1) Cut the chicken into 24 bite-sized pieces. Combine sesame oil, 1 tablespoon of the mirin and 2 teaspoons of the soy sauce in a small bowl and add the chicken pieces. Toss well to coat and marinate for 30 minutes or overnight.
2) Slice the leeks into 24 pieces, approximately 2.5cm (1 in) long. Thread 3 pieces of leek and 3 pieces of chicken onto each skewer, alternating.
3) To make the sweet soy dipping sauce, combine the sauce ingredients in a small saucepan and stir over medium heat until the sugar dissolves. Remove from hear and pour into 4 small dipping sauce bowls.
4) Grill the skewered leek and chicken under a pre-heated broiler or over a barbecue grill for 5-6 minutes on each side or until browned. Served with lemon wedges and sweet soy dipping sauce.
Source: Periplus Mini Cookbooks (Japanese Favorites)