Grater is a kitchen utensil used to grate foods into fine pieces. It was invented by François Boullier in the 1540s, originally to grate cheese. In Sushi, it is mainly used to prepare condiments because it enhances intrinsic flavors and retains more nutrients. It produces shreds that are thinner at the ends than the middle. This allows the grated material to melt or cook in a different manner than the shreds of mostly uniform thickness produced by the grating blade of a food processor. These include wasabi, ginger,and daikon radish. With the exception of wasabi a metallic grater is used to grate the root, or vegetable. The wasabi requires a grater with finer teeth so it can release the compounds that have anti-bacterial properties, and the strong spicy taste as well.
Some of the best sushi graters are available here.