There are two types of breakfast in Japan, the Western one involving bread and the traditional one involving rice. For me I find it easier to stick a piece of bread in the toaster, cut up some fruit and scoop out some yogurt into a cup in the mornings. I do however enjoy the Japanese breakfast, usually when I stay over at a hotel.
Did you know the famous, widespread chain, Yoshinoya, famous for their gyu-don (beef bowls) serve up a very affordable Japanese breakfast? They open quite early for those that have to get to work early, and the breakfast menu is available until 11am. Items on the menu include salmon, mackerel, salad, a small bowl of their simmered beef, natto, ham and eggs. All of their set meals include rice and miso soup. It's a simple breakfast that at a hotel would cost you a bit, but Yoshinoya is also known for their very affordable prices, so you could eat a full breakfast for only 338-548 yen!
Here I ordered the salmon, natto and natto breakfast (538 yen) and swapped the miso soup with asari jiru (miso soup with clams) for an extra 93 yen. This particular branch also had a side of jako oroshi (small Japanese sardines with grated daikon). Although nothing really stands out besides the volume and price, it sure was a satisfying breakfast of champs.