Combine the shoyu, honey, pepper flakes, and sesame oil in a zip-top bag and shake it all together. Then add the chicken. Let the chicken marinate refrigerated overnight, or at least 1 hour.
After marinating take the chicken out of the bag and dry it off with paper towels.
Beat the egg, add the water and garlic powder, to taste. Don't be afraid of the garlic here, but don't go vampire hunting either.
Heat the oil in a frying pan over medium/medium-high heat. Be sure to watch the oil, if it begins to smoke - turn it down a notch.
Dredge the chicken in the rice flour, then egg, followed by the panko. Place the cutlet into the pan and fry for 5 to 8 minutes on each side. The panko should be crispy and golden brown. Place on a drying rack and finish frying the other pieces.
I like to serve this with sunomono and potato-mac salad.