Precautions before use / Prevent chip, re-sharpen
Post-purchase and usage habits of kitchen knives differ between the world and Japan.
It is very important that consider the edge and blade whether thin or thick before use. Otherwise, your usual usage of kitchen knives and habits will chip the edge.
Our knives are sharpened and can cut papers easily. However Japanese professional chefs usually re-sharpen to their preferred blade angle before use.
If you cut hard ingredients, re-sharpen the edge and blade to an obtuse angle. If you only cut soft ingredients, sharpen them to an acute angle. Of course, if the blade and edge have the desired angle from the beginning, there is no need to re-sharpen it.
Don't twist edge, and don't cut and hit frozen ingredients or bones. Do not cut it like hitting it or put much force on it. The edge will be chipped or broken.
About rust, Carbon steel gets rust. Even if it is handled properly, it will be difficult to completely avoid rust. Some customers think knives that gets rust easily are defective, but that's not true. Even very expensive kitchen knives made of high carbon steel will rust after being soaked in water for a short time. So you've probably seen Japanese sushi chefs wipe Sushi knives with a cloth every time they cut.
After use, it is important to clean it well and dry it well. If you do not use it for a long time, it is recommended to apply oil and store it. If rust appears, sharpen it with a whetstone of 5000 or above to prevent rust from appearing afterwards.
Acidic foods and salt accelerate the development of rust.