This is the Ginsan version of the Tetsujin Tanryusen (Metal Flow). The cladding is the same soft iron, hand-forged so the layers show a clear forging cloud. You usually see that look on knives clad in old wrought iron, which is rare and expensive; here it comes from forging and sharpening technique, and etching brings the pattern out.
The difference is the core. Ginsan (Hitachi Silver #3) is a fine-grained stainless steel, hardened to 60-62 HRC, so it takes a keen edge the way carbon steel does while the core itself resists rust.
The iron cladding still reacts, so wipe it dry and expect it to darken with use. If you want the Tanryusen look with an easier-going core, this is the one; if you prefer carbon steel, go for the Blue 2 version.
