Edo was the premodern name of Tokyo,
and it was there that nigirizushi originated
and flourished for a long time before spreading to other parts of Japan.
Nigirizushi consists of a little fistful of Sushi rice on top of which some wasabi is smeared.
On top of this a slice of raw fish or other seafood is placed.
Octopus and prawns are cooked, squid is not.
Omelet is also used and so are both salmon roe (ikura) and sea urchin (uni).
These latter two are kept in place by a strip of nori around the rice.
Nori is also used to hold blanched Daikon sprouts (kaiware) in place.
Among the favorite sushi toppings are toro, ebi, shako, anago, ika, tamagoyaki,
and many kinds of raw shellfish.
Nigirizushi is eaten, preferably in one mouthful, after the topping is dipped in soy sauce.