What is Kirihadzukuri in Japanese Katana terminology?

"Kirihadzukuri"(切刃造り) refers to a type of sword construction, also known as ""Ryoukirihadzukuri"" (両切刃造).

This style of construction was prevalent during the era when straight swords (Chokutou) were the mainstream, before the appearance of curved swords (Wantou) with a bow-like curve. A distinctive feature of this style is that the ridge (Shinogi) is closer to the blade side.

It is said to be the precursor to the typical Japanese sword construction, ""Shinogi-zukuri"" (鎬造り).

In addition, there is ""Katakirihadzukuri"" (片切刃造), which appeared in the late Kamakura period. ""Katakirihadzukuri"" is a construction seen in short swords and Wakizashi made during the Nanboku-cho period and the early Edo period. The characteristic of this construction is that only one side becomes a cutting edge."