What is Yakidashi in Japanese Katana terminology?
Yakidashi refers to the blade pattern (Hamon) near the "区" (Machi: notch) where the tempered blade part begins. In many swords, the tempering starts from the lower part of the "刃区" (Hamachi: notch on the edge of the blade), and as it goes up the body, the characteristic blade pattern (Hamon) of each swordsmith appears. If the upper body is an irregular blade (Midareba), but the beginning of the tempering is a straight blade (Suguha), it is called a straight blade Yakidashi. Conversely, there are also swords that have deep tempering only in the Hamachi part, called "腰刃" (Koshiba), and swords that have a straight blade in the upper body but have a Gunome (a series of round patterns creating a bumpy shape) only near the Hamachi.