Sasaoka-san and his brother make these knives out of Tosa,  using blue carbon steel.

It is single bevel and clad in soft iron, so it is more susceptible to rust. Please take proper care of this knife and it will serve you well. 

Specifications:

• Brand:Akira Sasaoka
• Edge Steel: Aogami 2
• Cladding: Soft Iron
• HRC: 61-63
• Length : 270mm
• Handle: Cocobolo and Buffalo horn

Use & Care

• Do not attempt to cut, hit or chop frozen products or bones. The blade can chip or break with improper use.
• Hand wash with warm water and towel dry. Never put the knife in a dishwasher, nor soak it in water. Ever!
• Use a sharpening stone to maintain the sharpness of the blade. 
• Do not use on hard melons or items that may torque the blade.
• Use a sharpening stone to maintain the sharpness of the blade.