和食 朝食 - Google Search
Rice, miso soup, some kind of fish(Salmon or Mackerel is common), an egg of some style(Japanese omelet, fried, poached or… raw), some veggies (stir fried, boiled, pickled, etc.), and in some areas including Tokyo, Natto (fermented soy).
Western style breakfast is pretty popular too, although you never mix some of the things with Japanese dishes, like cereal and Natto sounds impossible. A lot of people do something like egg, sausage and rice.
My breakfast consists of milk, coffee beans and water...