Update: 29 December 2016
While fast food chains like McDonald's are globally famous around the world, here is a brief history and examples of Japanese fast food.
The History of Japanese Fast Food
Looking back through history, sushi and tempura are said to be the beginnings of fast food in Japan. Due to a system where daimyo (feudal lords) had to spend every other year in Edo, many samurai came to Edo, leaving their wives and children at home. It is said that cheap and easy-to-eat restaurants were made for such people. There were restaurants for sushi, soba, tempura, and oden. In the 1970s, American-style fast food came to post-war Japan, and Japanese people began using the phrase "fast food".
Gyudon is a bowl of rice topped with beef, onions, and other ingredients. There is also butadon, which is topped with pork and onions that were boiled in soy sauce and sugar. There are also other various bowls that are topped with natto, walleye pollock roe, cheese, and so on.
Tachigui (Stand and Eat) Udon and Soba
In the station yards of Japan, you may often come across shops called things like Tachigui Udon and Tachigui Soba. They say their origins come from the food stalls of the Edo period, and you can now see such restaurants at train stations, highway rest stops, baseball stadiums, race tracks, and more. The menu is written on a ticket machine at the entrance, and you buy your meal ticket there, which you then pass on to the staff once you enter the shop.
An onigiri is made by cooking rice, potentially seasoning or putting other ingredients into it then molding it into the shape of a triangle or ball. Originally they were a way of preserving leftovers, and were used by families to save leftover rice or as portable food. Currently, since they are so handy, they are sold at convenience stores and bento (boxed lunch) stores.
Other Japanese Fast Foods
Other items that were developed as fast foods are curry rice and ramen. Each with their own distinct flavors and varieties.
*This information is from the time of this article's publication.