The word “sushi” actually refers to the seasoned vinegared rice, not the fish itself. Traditional sushi chefs in Japan train for many years to master rice preparation, knife skills, and seafood handling. Wasabi served with sushi was originally used for its natural antibacterial properties. Soy sauce is traditionally used lightly so it does not overpower the balance of flavors. Nigiri sushi became popular during the Edo period in Tokyo as an early form of fast food.