Kikuichi Carbon Steel This Kikuichi Yanagi Sashimi knife is Tatsutogi Grade and is made of high quality carbon steel. The knife comes with a free saya cover or sheath. Right Angle Blade, Ho-Wood Handle. Our TATSUTOGI knives are made out of SK grade high carbon steel. SK steel is widely used for fine and expensive carpenter tools as well. SK is approx. 60 to 61 HRC.