Season chicken breasts with salt and pepper.
Dredge in flour, then egg, then panko.
Fry in oil at 350°F (175°C) for about 4 minutes per side, until golden brown.
While resting, thinly slice onion and beat the eggs and yolks.
In a pan, combine dashi, soy sauce, mirin, sake, and sugar. Simmer.
Add onions and cook until wilted. Add sliced katsu, then pour eggs over and cover until eggs are just set.
Serve over rice, garnish with scallions if desired.
