Butterfly the chicken to even out the thickness. Season the chicken with salt, black pepper and garlic powder. It tends to be better when it's generously seasoned.
Grill until golden brown (about 20 minutes inside my induction stove). Meanwhile grate some daikon radish and slice the scallions.
Cut into bite-sized pieces and plate them when cooked.
Garnish with plenty of grated daikon radish and scallions, and sprinkle on some ichimi spice to taste. Pour ponzu sauce over it and your dish will be ready. Squeeze some sudachi or yuzu if available.
Substituting shiso leaves for the scallions is delicious too.