What is Sun-nobi tanto in Japanese Katana terminology?

"Sun-nobi tanto"(寸延短刀) refers to a type of Japanese sword that, despite exceeding the typical length of a ""tanto"" (短刀), which is usually under one shaku (approximately 30.3 cm), is still classified as such due to its specific characteristics. These characteristics include a blade that has little to no curvature and a flat construction without a ""shinogi"" (鎬), which is a ridge line running along the length of the blade.

The Sun-nobi tanto first appeared during the Nanboku-cho period (a period of Japanese history spanning from 1336 to 1392) and was widely produced from the late Muromachi period (a period of Japanese history spanning from 1336 to 1573) to the early Edo period (a period of Japanese history spanning from 1603 to 1868).

This type of sword reflects the changing needs and circumstances of the samurai class during these periods. The longer length and flat construction of the Sun-nobi tanto would have made it a versatile weapon, suitable for both cutting and thrusting. The fact that it was widely produced during these periods underscores its popularity and effectiveness as a weapon."