People in Edo started to have Sushi and a restaurant started using fresh fish.
'Edo' means old Tokyo during from the 17th to 19th centuries where used to be a city of Samurai, and Osaka is for merchant at the time.
Uni (Sea urchin)
And NOW, Sushi chef in Osaka cut up a fish from stomach but chef in Tokyo do it from back.
Because Harakiri (commit ritual suicide by disembowelment) is avoidable for Samurai, and Hara wo waru ('Breaking stomach' means heart to heart talk) is high end spirit for merchant.