What is Tsurehi in Japanese Katana terminology?

The term "Tsurehi" (連樋, つれひ) refers to a specific type of groove (Hi) carved into a Japanese sword. This groove is a type of "Soebi" (添樋), which is a narrow groove carved parallel to a larger groove known as "Bohi" (棒樋). What distinguishes Tsurehi from Soebi is that the Tsurehi extends all the way to the tip of the Bohi. This design element not only enhances the aesthetic appeal of the sword, but can also serve practical purposes, such as reducing the weight of the blade or improving its balance. This terminology is used to describe the specific characteristics of the sword's structure, contributing to its overall aesthetic and functional design.