With a coarse grinding stone, the blade grinding starts. The shape of a blade (cutting edge) is formed at this stage. Rough sharpening scrapes the "stainless" part on both the front and the back sides, and exposes the "steel" in the center.
Since the "blade" is to be created by scraping a very stiff metal after the heat treatment is complete, although the water grinder is used, it is a physically demanding work.
Because it is not polished automatically by machine, considerable skills are required to obtain the evenness of steel.