In a mixing bowl, whisk together the eggs, soy sauce, mirin, sugar, and salt.

Heat vegetable oil in a non-stick frying pan over medium heat.

Pour the egg mixture into the pan, tilting the pan to spread the mixture evenly.

Cook for about 2 minutes until the bottom is set.

Using a spatula, fold the omelette in half and continue cooking for another 2 minutes.

Transfer the omelette to a cutting board and slice into pieces.

Serve hot and enjoy!