Kai USA Ltd. distributes Japanese-made Komachi 2 knives in the United States. The blades are made of high-carbon stainless steel and coated with a special non-stick resin. Komachi knives are famous for being razor sharp and holding an edge. However, like all knives, the Komachi 2 blades must be sharpened once the edge becomes dull. Kai recommends a Japanese whetstone for the task.
Place the 1,500-grit Japanese whetstone on a flat surface such as a kitchen counter. Place a rubber mat under the whetstone if it does not have a non-slip base. Place the rectangular stone lengthwise so that it is parallel to the line of your shoulders.
Apply a thin layer of water to the whetstone's surface with your finger. Wet the entire surface.
Hold the Komachi knife in your dominant hand. Place the heel of the knife near the lower right corner of the whetstone with the cutting edge of the knife facing left. Hold the knife against the whetstone with the blade at a roughly 16-degree angle. Estimate the angle by following the factory angle on the blade as close as possible. Hold the knife so that it is almost parallel to the whetstone with the tip pointing to the right.
Draw the knife in an arc to the left and toward your body while rotating the tip of the blade through the arc until it is perpendicular to the whetstone. Maintain the 16-degree tilt as you pass the Komachi through the arc. Use your other hand to apply slight pressure and to guide the knife through the arc. The knife will complete the arc with the tip almost passing through the lower left corner.
Flip the knife over so that the blade faces right. Place the heel near the bottom right corner of the whetstone. Use the same technique as before to draw the Komachi through the sharpening arc.
Repeat the sharpening passes a few times on both sides. Test the sharpness of the blade by slicing a tomato or sheet of paper. The Komachi will slice through either with minimal effort once the blade is properly sharpened. Repeat the process until the blade achieves the desired sharpness.