An Unagisaki Hocho Knife is a special knife for filleting eel.
The blade would be rectangular, except its nose is a straight 45 degree angle from top to bottom. This creates a sharp tip or piercing the head of an eel, and then dragging the knife along its body to slice it open along its entire length in one continuous motion.
The blade style varies slightly in Kyoto, Nagoya and Osaka.
Language Notes
“Unagi” means “eel”; “hocho” means “knife”.