Edomae means in front of Edo, which is to say Edo bay, and originally it described nothing more than where the fish had come from. Nigiri sushi in a form we would recognize appeared in the early nineteenth century, during the late Edo period.

The city at that point held a million people, a great many of them single men living alone, and the food stalls selling sushi, soba, and tempura did an enormous business among them. There was no refrigeration anywhere in this arrangement.

So the fish could not simply be sliced and served as it was. It was cured in vinegar and salt, or simmered, or steeped in a sauce, and only after that was it pressed onto a bed of rice. Those preparations are what the trade calls shigoto, the work, and the whole vocabulary of technique that surrounds high-end sushi today descends from the problem of keeping fish edible for one more day.

The pieces were two to three times the size of a modern one. This was fast food, eaten standing at a stall by somebody who wanted to stop being hungry. The refinement came a good deal later. The methods came first, and they arrived out of plain necessity rather than from anyone's idea of what was elegant.