Sujihiki translates as "flesh slicer", which describes its role well. Typically 240 mm to 300 mm long and 34 mm to 40 mm high, the sujihiki blade is perfect for making long cutting movements from heel to toe. A lower blade height decreases friction when cutting and keeps the fibers of the protein you are cutting as intact as possible.
Super Gold 2 or SG2 is a powder metallurgy steel developed by Takefu Special Steel Co Ltd in 1991 in Takefu, Echizen, Fukui Prefecture. It is a high carbon stainless steel that is pulverized into very fine grains. These are then put back together. This process results in a homogeneous grain structure, making it easier to sharpen and very durable. SG2 can reach a hardness of 64 HRC, making it a very famous steel in the Japanese cutlery world.
Takefu Special Steel Co Ltd, creator of the popular VG-10 steel, wanted to offer with SG2 a superior product in all aspects of hardness, cutting retention, durability, etc.
Today, the company no longer manufactures SG2. The SG2 knives on the market are, most of the time, made of almost identical steels and are manufactured by other companies. For example, Kobelco's R2 has the same characteristics as the SG2.