Sushi was originally developed as preserved food.
It was popular as first food in the Edo period…
This type of sushi was well-known for Edomae (Edo-style) sushi.
Food preservation devices were not yet found around that time, so sushi chefs came up an idea to preserve fresh fish placed on top of sushi and even further to bring out its flavor with their profession.
People at that time enjoyed eating seasonal fish placed on top of sushi as well as feeling the changing seasons.
In this manner, sushi is a food that is deeply associated with Japanese history and culture.