Ginsan steel, also known as Silver #3 or G3, is a stainless steel made by Hitachi Special Steel in Japan, containing 1.02% carbon and 13.75% chromium, and it is used in Japanese knives because it combines the sharpness and ease of sharpening of carbon steel with the rust resistance of stainless steel. It is a fine-grained steel that takes a very sharp edge, and at a hardness of 60-62 HRC, it offers a practical balance of edge retention and sharpenability for everyday kitchen use.

The name "Ginsan" (銀三) literally means "silver three," referring to its Silver #3 designation. Its moderate chromium content makes it far less reactive than carbon steels, so it won't discolor or rust as quickly, while its carbon content keeps the edge keen and responsive on the stones. For home cooks and professionals who want a stainless knife that still feels like a traditional Japanese blade, Ginsan is a common middle ground.

The Hatsukokoro by Nakagawa Ginsan Single Bevel Mirror Polish line consists of Yanagiba and Deba knives forged by Satoshi Nakagawa using Ginsan steel with a flat zone (Hira) finished in a refined mirror polish, designed primarily for professional chefs and serious enthusiasts who prioritize aesthetics alongside function.

These knives are built for those willing to manage a high-budget tool where the mirror finish offers a sharp, uniform look but requires more care to maintain than a standard Kasumi finish. While the entire blade features consistent grinding marks, a rounded choil and spine, and the same construction as the Kasumi line, the mirror polish itself can be difficult to keep pristine, making it a trade-off between visual appeal and ease of maintenance.