Thinly slice the onions and ham. Shred the shimeji mushrooms and set aside.
Wash the rice. Use about 2 cups worth of water in the cooker, combined with the ketchup. Add salt, lightly stir, and cook in the rice cooker.
Once the rice has cooked, heat 1 tablespoon of butter in the frying pan. Beat one egg well (1 serving) and add.
Use chopsticks to make a large mixing motion a few times. When it's half-cooked, turn off the heat. Be careful not to over-cook.
Transfer the rice to a serving plate and put the egg on top. If you would like, pour ketchup on top.
Story Behind this Recipe
I don't like the wrapping process for omurice.
To get the eggs soft and half-cooked, I recommend lots of butter. It'll be high in calories though. Making ketchup rice in the rice cooker is easy. Just remember to wash the pot and the rice spoon well afterwards.