What is a typical Japanese breakfast?
Fish, natto, rice & miso soup
What Japanese call breakfast would be considered more like lunch for Westerners. A typical Japanese breakfast consists of rice, miso soup, fermented soybeans (natto), grilled fish, some pickled vegetables and a small salad. Although many Westerners would rather skip the natto, it's still a well-balanced and healthy meal.
A lot of people on the run will simply catch a bowl of gyudon (beef and onions over rice) or a bowl of ramen. It's cheap, filling and quick. Perfect for the salarymen cut up in the hustle and bustle of Tokyo. A regular size of gyudon is less than ￥500 and is about 700 calories. So it's a good bang for your buck.
Onigiri also fills the cheap, filling and convenient criteria! A lot of restos and onigiri-specialized shops, conveniently located in stations are really nice. You can get, for example, an onigiri with a piece of fish in the centre. It's super easy to grab on the go and it's usually around ￥200-￥300.
Another typical breakfast in Japan is coffee with thick pieces of toast. With a clear Western influence, the Japanese have put a spin on the classic breakfast and often serves it in an old-style Japanese cafe with a hand-drip cup of coffee and some red bean paste. It's quite tasty, you should give it a go too!