Teriyaki means broiling with soy sauce and sweetened sake. Yellowtail is often broiled together with soy sauce and sweetened sake. In that recipe, yellowfish tends to become tough.
In this recipe, after being dealt with salt, yellowfish is wrapped with aluminum foil and is broiled as it is usually cooked. Soy sauce, sweetened sake and sugar are cooked while fish is getting grilled. Sliced ginger is added to the sauce. Finally, the viscous sauce with ginger is put on the broiled yellowfish. Yellowfish remains soft and tasty.
I bet this recipe will enable you enjoy one of the first quality yellowfish dishes, which you could enjoy only at a traditional reataurant in Japan.