Usuba Knives Usuba Knives are traditional Japanese vegetable knives and used primarily in Japanese restaurants. They are typically ground with a single bevel on the right side of the blade and most come with a hollow ground back. The knives are not as popular as the similar looking Nakiri knives that have a double bevel and which are easier to learn to use and control. Most but not all Usuba knives come in 165-210mm and typically use carbon based steels. There are exceptions to both of these generalizations.