Cut the chicken breast and onion into bite-sized pieces.
Beat the eggs in a bowl and set aside.
Heat cooking oil in a pan and sauté the onions.
Add the chicken breast and cook together.
Add soy sauce, mirin, sugar, and water, then bring to a boil.
When the onion and chicken are cooked, pour the beaten eggs over them and cook on low heat.
Put cooked rice in a bowl and top it with the prepared ingredients.
Garnish with green onions and seaweed flakes.