Mince the green onion.

Mix natto in a bowl, then add beaten eggs, minced onion, and a pinch of salt and pepper. Stir well to create the egg mixture.

Place cooked rice in a serving bowl. Heat sesame oil in a frying pan over medium heat, pour in the egg mixture, stir gently, and cook until semi-set. Remove from heat and place the egg mixture over the rice.

In a saucepan, combine sugar, vinegar, soy sauce, chicken stock powder, water, and cornstarch. Heat over medium heat, stirring constantly, until the sauce thickens.