Cooked rice mixed with sushi-vinegar in which sugar and salt are added. In sushi term it is called “shari”. It is said that fish ingredient counts up 40% and shari is responsible for 60% to make tasty sushi. Bad-taste shari spoils entire sushi even if good fish ingredient is used.
Then when you put the sushi in your mouth and bite down, it should ideally come apart to fill your mouth easily, the shari should have harmonious synergy with the topping, and it should pass down your throat smoothly. The right temperature for sushi is around skin temperature, so that the chef can make it comfortably.