Omelet filled with crab, leek slices, bamboo shoot slices and mushroom slices. かに玉。
The omelet is sometimes covered with a thick sauce seasoned with sugar and soy sauce. This is the Japanese (Chuka) version of Egg Fu Yong, the Chinese dish where any leftovers from fish or meat can be added to the omelette.
Real crab is, however, rare. You usually find crabstick (imitation "crab" made from fishcake).
[Photo Ad Blankestijn]