Shiro Kunimitsu knives. Great knives from sword maker smiths from Fukuoka Japan. Yasuki steel (White #1) is forged between layers of stainless steel. The heat treatment on these is about 61 Rockwell. This is done to prevent the blade from rusting. However, it is important to wash the knife thoroughly after each use and to wipe dry with a clean cloth. The proper way to cut is to use a slight pressure while pulling back and forth, rather than pushing down on the knife.