What is Habaki-shita in Japanese Katana terminology?

The term ""Habaki-shita"" (鎺下, はばきした) refers to the part of a Japanese sword that is hidden by the ""Habaki"" (鎺). The Habaki is a metal fitting used to secure the blade within the scabbard (Saya). Therefore, ""Habaki-shita"" refers to the area from the edge of the blade (Hamachi) to the rusted edge that is concealed by the Habaki.

The Habaki has been seen in its original form since the Kofun period. The purpose of the Habaki is to prevent the blade from touching the inside of the scabbard and to securely fit the blade into the scabbard when sheathed. In the past, the Habaki was made together with the blade, and these are referred to as ""Tomohabaki"" (共鎺).

In modern times, it is common to remove the Habaki for the appreciation of Japanese swords, making the Habaki-shita visible. However, before the Edo period, the Habaki was rarely removed except for when the sword was being reconditioned or polished."