A traditional Japanese breakfast is likely different from any other kind of breakfast you'll ever experience. It consists of foods that make up a complete meal that one could conceivably enjoy at lunch or dinner.
Typically, a traditional Japanese breakfast consists of steamed rice, miso soup, a protein such as grilled fish or rolled egg omelette (tamagoyaki) and various side dishes. Familiar side dishes may include tsukemono(Japanese pickles), nori (dried seasoned seaweed), natto (fermented soy beans), kobachi (small side dishes which usually consist of vegetables), and green salad.
Although a Japanese breakfast comprises what others might view as a complete meal appropriate for lunch or dinner, it is not intended to be heavy or too filling. Portion sizes for breakfast are adjusted to meet one's appetite, and dishes tend to lighter. for example they tend not to be greasy, deep fried, or rich.