Tamahagane knives are manufactured by Kataoka and Company in Niigata, Japan. The word tamahagane means precious steel. Historically, the word tamahagane has been known as a particular, very pure and high-quality steel produced using traditional Japanese techniques. Today, Kataoka uses Tamahagane as the brand name for the exceptional knives it makes from similar quality steels produced using modern techniques. With their unsurpassed sharpness and edge retention, these knives are definitely precious steel.

San Kyoto:

The SAN KYOTO Tamahagane knives feature 63-ply stainless steel construction. The core or middle layer is VG No. 5. The core layer is the cutting edge and is 61 degrees on the Rockwell scale for hardness. There are 31 layers of SUS410 stainless steel on each side of the middle layer. These 31 layers on each side create a beautiful damascus pattern which make the knives very distinctive. The outside layers are softer and more stain resistant than the cutting edge and actually protect the cutting edge.
The 63-ply stainless steel has an original thickness of 20 mm and is thinned by repeated rolling to a thickness of 2 mm. You might want to look at this rolling process as a modern forging technique. Also, this rolling process removes all the impurities in the steel leaving you with a very hard, very pure stainless steel. After the rolling processes, the V-G No. 5 cutting edge reaches a hardness of 58-60 degrees on the Rockwell scale and a final thickness of .65 mm. The outside layers each reach a thickness of .675 mm.
There are several different VG stainless steels. Kataoka selected V-G No. 5 stainless steel for the SAN KYOTO knives, because V-G No. 5 can be hardened as hard as any of the other V-G steels but has superior edge retention. Using scientific testing equipment (CATRA), Kataoka was able to show that their knives stayed sharper longer than knives made from other VG steels.
The edge on the SAN KYOTO knives is a minute, beveled edge. The angle of the edge is between 14 and 15 degrees. To appreciate the quality of the edge, you must first look at its incredible mirror polish and then try cutting with it. Kataoka has achieved the perfect balance between sharpness and strength with the SAN edge.
The SAN KYOTO knives are balanced with a stainless steel weight which attaches to the tang and is visible at the heel of the handle. Not only does this add to the beauty of the SAN KYOTO design, it also creates fantastic balance.
The SAN KYOTO uses a black Mikarta handle which is resin laminated with linen. The handle shape is distinctive yet classic. The tang is completely concealed so that it cannot be a source of discomfort. The handle fits very comfortably in the hand.