The Tamahagane San series has a 3-ply steel. The center (Core) layer is VG5 and the outside layers are SUS410. Except the SN-1120 which has a "solid blade". The blade material of 3 layers with the original thickness of 20.00 mm has been thinned to the final thickness of 2.0 mm by rolling processes repeatedly applied.
After the rolling processes,the material of VG5 becomes harder and harder to be 58-59 Rockwell Hardness in the final thickness of 0.65 mm. Meanwhile, the two outside layers of SUS410 will remain at 28 to 32 RC to strengthen the blade and protect against damage and corrosion. This is the outstanding feature of the knife.The blade is sharper and holds its sharpness longer than normal knives.