Heat a little butter in a frying pan. Sauté the onion, sausages, and corn. Add the cooked rice, season with black pepper and ketchup, and stir to combine.

Heat butter in a frying pan and cook the eggs to make a thin omelet.

Once cooked, place a sheet of plastic wrap on a plate, put the omelet on it with the side you want to show facing down.

Line your bento box with plastic wrap, add the rice mixture, and gently shape it to fit the omurice style.

Place the shaped rice onto the omelet, with the gathered side of the wrap facing down. Carefully peel off the top layer of plastic wrap. This is a key step!

Hold the plastic wrap under the omelet and shape it into an omurice form.

Place the wrapped omurice into the bento box with the gathered side down, then gently remove the top layer of plastic wrap again. This is another key step!

Fill any empty spaces in the bento box with your favorite side dishes.

Drizzle ketchup on top and it's ready!

If you're worried about ketchup getting messy when you close the lid, I found a solution!

There are small containers for ketchup or dressing. Put them in the bento and add the ketchup just before eating to keep things neat!