Another characteristic of Japanese knives is that the back side of the blade is not perfectly flat, but is hollowed out.
This is called “Urasuki” and is sometimes called “Urahiki” among craftsmen.
This Urasuki is a very excellent structure that gives various effects to Japanese knives.

It improves the separation of the blade from the food when it is cut.

It is common for the blade to stick to the food when cutting it, but this is because there are many points of contact between the blade and the food. Single-edged blades have a structure that allows for good separation of the blade from the food, but the back of the blade is concave on the back to allow for even better separation of the blade from the food.
The back of the blade is concave, so there is a gap between the blade and the food at that point, which prevents sticking.

Easy to sharpen the back

The dented backside means that when the grinding stone is applied to the backside, it hits the cutting edge.
Therefore, it is easy to remove the gouges by just sharpening with light force.
The backside of the knife is the foundation of Japanese kitchen knives, and plays an important role.

*This is a translation by a translation tool.