Combine sugar, Mirin Sauce, cooking Sake and Soy Sauce into a small saucepan and bring to boil. Lower heat to medium and simmer for a minute. Set aside.
Score the chicken and dust the chicken with flour.
Heat a pan over medium-high, add cooking oil and cook the chicken through – cook skin side first.
Add 120ml – 160ml of Teriyaki sauce in the pan and cook until the sauce becomes thicker and lightly caramelized.
Slice the chicken and serve on a plate. Garnish with chopped spring onion or toasted sesame seeds if desired.