No, Japanese steel is not the same as stainless steel. While both types of steel have their own characteristics and applications, they differ in terms of composition and properties.

Japanese steel, particularly the traditional steels used in Japanese sword making, such as Tamahagane, is often high-carbon steel. These steels have a relatively higher carbon content, typically ranging from 0.5% to 1.5%, which contributes to their hardness, sharpness, and edge retention. Japanese swordsmiths carefully smelt and forge these steels to create blades with specific characteristics, including the ability to maintain a keen edge and endure rigorous use.

Stainless steel, on the other hand, is a type of steel alloy that contains a minimum of 10.5% chromium by mass. The addition of chromium provides stainless steel with corrosion resistance properties, making it less susceptible to rust and staining compared to other types of steel. Stainless steel is often used in applications where resistance to corrosion is essential, such as cutlery, kitchen utensils, and various industrial and construction materials.

It's important to note that stainless steel can have varying degrees of hardness and edge retention, depending on its specific composition and heat treatment. While some stainless steels can be hardened and sharpened to a good extent, they generally do not exhibit the same level of hardness and edge retention as high-carbon steels used in traditional Japanese sword making.

In summary, Japanese steel, particularly the traditional steels used in sword making, is often high-carbon steel prized for its hardness and edge retention. Stainless steel, on the other hand, is a different type of steel alloy that provides corrosion resistance but may not have the same characteristics as traditional Japanese steels in terms of hardness and sharpness.