When it comes to grilling fish, the Japanese have mastered the art. Which should hardly be surprising, when at least according to the Guardian "one in ten fish is eaten in Japan. " As a culture Japan has explored the eating of fish to levels quite literally never even thought of yet in the west. We have plenty of sushi bars in the States, but the food served at most American sushi bars is a very narrow range of possible selections you could make of Japanese fish dishes.
The cooking process is what makes the eel both crisp and tender: The eel is first grilled over hot oak charcoal, then steamed to remove excess fat, then seasoned with a sweet barbecue like sauce and grilled a second time.