To prepare the sauce, combine the sugar, mirin, soy sauce and saké in a saucepan and bring to a boil. Reduce the heat to low and simmer for 15 minutes, reducing the sauce to 1 cup.
Cut the chicken and liver into cubes, then thread them through the skewers, alternating with pieces of the mushroom, leek and bell pepper. If bamboo skewers are used, soak the