In the midst of my excitement over sushi buffets, I remind myself to take what the restaurant crew have just brought out... Raw food sitting long hours on the table calls for a Salmonella* gathering (*bacteria that causes typhoid fever & other food-borne illnesses).
Flavor & texture of FISH is best enjoyed raw when it's extremely fresh. Otherwise, you're better off cooking it, or seasoning then grilling. Seriously, I'd never attempt to buy fish from the grocery then bring it home to eat raw! Dine at some reputable place as much as possible to avoid the risk of being food poisoned.
(I hope this post doesn't make you paranoid. Enjoy your Japanese food, but eat it fresh! Better safe than sorry...;)