Cut the chicken breast into bite-sized pieces
Slice the onion thinly
Beat the eggs in a bowl
Heat oil in a pan and stir-fry the chicken breast
Once the chicken is cooked, add the onion and stir-fry
Add soy sauce, mirin, water, and sugar, then bring to a boil
When the sauce is boiling, pour in the beaten eggs and cook until set
Serve the cooked ingredients over rice