"Nagasa" refers to the length of the blade in a katana. In the context of a katana, "nagasa" specifically refers to the length of the cutting edge of the blade, excluding the tang (nakago) that extends into the handle (tsuka).

The term "nagasa katana" is not a specific type or variant of katana but rather describes the length of the blade. The length of the nagasa can vary, but traditionally a katana has a nagasa of around 60 to 73 centimeters (approximately 24 to 29 inches).

The length of the nagasa affects the overall balance, weight distribution, and handling characteristics of the katana. Different swordsmiths and schools may have slight variations in their preferred nagasa length based on personal style or regional traditions. However, the general range mentioned above is considered standard for a traditional katana.

It's worth noting that the length of the blade alone does not define a katana as there are other features and characteristics that make up a complete katana, such as the curvature, hamon (temper line), tsuba (guard), and tsuka (handle).