Put 3 tbsp of ketchup, sugar and 2 tbsp water in a flying pan and melt butter over medium heat and set aside the ketchup sauce.

Finely chop onion, mushrooms, and cut chicken into bite sized pieces.

Melt 5g butter in a flying pan over a medium heat, stir fly the chicken thigh in butter.

Add the onion and mushroom to cook over low-medium heat. Sprinkle salt and pepper, add cooking wine and 3 tbsp ketchup.

Add rice and stir fly it till brown. Set aside in a bowl.

Dissolve mayonnaise in 2 tbsp water and mix well.

Crack the eggs into a bowl, and mix in the mayonnaise mixture. Add salt and pepper.

Add vegetable oil and 10g butter into flying pan to melt.

Pour all of the egg mixture onto the pan and move it in a in a spiral motion as quickly as possible.

Put the chicken rice on the middle section of the egg and flatten the eggs on the edge onto the rice with a spatula.

Turn the pan over and place it on a plate and put ketchup sauce on the omuraisu.