“Rice omelet” is one of the very quintessential Western dishes that originated in Japan. When explaining about “rice omelet”, we should first explain about “chicken rice”, which is also known as a very typical Western dish originated in Japan. “Chicken rice” is a dish of chicken and onions cut into small pieces, stir-fried with rice and seasoned with tomato ketchup. In some restaurants, pork, sausage, or ham is used instead of chicken.
Other ingredients such as carrots, corn, green peas, or mushrooms are often added to the dish. Sometimes we call the dish “chicken rice”, which is just stir-fried (or cooked) rice with ketchup and no other ingredients. Around the Taisho era (beginning of 1900s), it is said to be originated from a dish prepared for poor children at a charity party held at a church during Christmas. They thought it would be a good idea to give the children something nutritious and satisfying to eat. “Rice omelet” is a dish of this “chicken rice” covered with an omelet. It was first invented around the end of the Taisho era ~ the beginning of the Showa era. Since then, it has become a standard menu dish at Western-style restaurants in Japan and is still popular today.
Incidentally… The technique of covering or wrapping some dish or ingredient with a thin egg is also used in other dishes today. “Yakisoba omelet” and “Fried rice omelet” are appropriate examples of such dishes. (※In Japanese, such dishes are called “Omu-○○”. Just like “Omu-rice”, “Omu-yakisoba”) Before this dish, “rice omelet” was invented, the cooking technique of beating eggs and baking them was not widely used in Japan. They were mostly boiled or steamed.
In the past, eggs were considered an expensive ingredient in Japan. As you know, they are very nutritious. Until about the end of World War II, eggs were still an expensive ingredient. Later, when the domestic egg production and supply network was stabilized, the consumption of eggs exploded. Japanese people are very fond of cooking with eggs. It may not be an exaggeration to say that “rice omelet” is the dish that started the Japanese love for egg dishes.