Filleted and deboned unagi is commonly glaze-grilled, and it's called unagi-no-kabayaki. It's skewered and grilled with sweet basting sauce, and is popularly served on top of steamed rice. Vacuum-sealed unagi-no-kabayaki is often available at Asian grocery stores.
Unagi-no-kabayaki is cooked differently in eastern Japan and western Japan. In eastern Japan, unagi is generally steamed after it is grilled, then it's grilled again. In the western part of Japan, unagi isn't usually steamed before grilling. So, unagi-no-kabayaki in eastern Japan is more tender than that in western Japan.