Nodaya

This video shows the Nodaya style unagi (eel) skewers of Nodaya .

Nodaya is a famous restaurant with a long history, established in 1953.
Its parent organization, "Nodaya Higashi-Seiki," was established in 1868 (the first year of the Meiji Period).
Nodaya has handed down traditional techniques for cooking eel and river fish since the Edo period, and has trained many chefs as the best eel and fish specialty restaurant in Japan's Kanto region.

From 1:29, there's an explanation of Nodaya's unagi skewers, and from 4:57, they show the actual skewering process
There are various types of skewering methods for the same eel, depending on the size of the eel and the dish, and you'll find that they are made with masterful techniques.
Be sure to check out the historic skills of this master eel chef!