Made from 145SC  Ultra pure carbon steel SC stands for Super Clean. 
At Lohmann in Germany Less then one ton was ever made of this steel from a brand new steel furnace thats how they could achieve the purity of the steel 
It was a project for Achim Wirtz 
Composition of the steel :
C = 1,44 – 1,46 %
Mn = 0,24 – 0,27 % 
Si = traces
P ≤ 0,006 % 
S ≤ 0,003 %
Fe = balance
First time ever Kato have agreed to make knives out of non Japanese steel because of its crazy purity 
Only made for JNS 
Yoshiaki Fujiwara - “The Workhorse”
These beautiful knives are made by Mr. Kiyoshi Kato, born 1944 in Tokyo. He began swordsmith training in 1964, at the age of 20, and is currently a licensed sword smith. He now uses his incredible collection of very old, and difficult to obtain, Tamahagane steels to form his own sword masterpieces. 
He entered the field of knife making in 1977 by creating his first hunting and kitchen knives, and currently makes knives in his new Hokuto City workshop, found in the Yamanashi Prefecture. 
Mr. Kato uses a special quenching technique, utilizing charcoal and water, which imparts an extra degree of hardness not often seen in regular clad knives.This gives all of his kitchen knives a feel very similar to Honyaki, incredibly stiff with little to no flex!
Steel: C145SC Carbon Clad (can rust !! ) 
Handle: Octoganal ebony Handle buffalo horn  Made In Sanjo 
Approx.. measurements:
Handle Length- 150mm
Handle Width- 25mm
Heel to Tip Length- 250mm
Blade Height at Heel- 53mm
Width of Spine at Handle- 5,5mm
Width of Spine Above Heel- 4,8mm
Width of Spine at Middle- 2mm
Width of Spine 1cm from the tip- 0,8mm
wight 268 g