Rinse 1 cup of short-grain Japanese rice under cold water until the water runs clear, then combine with 1.5 cups of water in a rice cooker and cook according to instructions, or boil and simmer on stovetop for 15-20 minutes. Let sit for 10 minutes before fluffing.

Melt 1 tablespoon of butter in a large skillet over medium heat, then add one finely diced onion and sauté for 3-4 minutes until translucent.

Add your choice of diced chicken, shrimp, or mixed vegetables, cooking for an additional 5-7 minutes until the protein is cooked and vegetables are tender.

Fold the prepared rice into the skillet and drizzle in 2 tablespoons of soy sauce and 1 tablespoon of ketchup, stirring for 2-3 minutes until heated through and well-coated.

In a non-stick skillet, heat 1 tablespoon of oil over medium-low heat. Beat 2-3 eggs until pale yellow and fluffy. Pour the eggs into the skillet, swirling for an even layer and cooking for 1-2 minutes until edges set and center is soft.

Scoop a portion of the rice mixture onto one half of the omelet and gently fold the other half over the filling, letting it cook for another minute.

Gently slide the folded Omurice onto a plate, drizzle with additional ketchup or demi-glace if desired, and serve hot.