What is Mitsugashira in Japanese Katana terminology?

The term "Mitsugashira" (三つ頭, みつがしら) refers to the point where the Shinogi-suji (鎬筋, the ridge line), the Ko-shinogi-suji (small ridge line), and the Yokote-suji (横手筋, the line separating the blade and the tip) intersect on a Japanese sword. Additionally, the intersection point where the Yokote-suji, the Fukura (ふくら, the curve of the tip), and the cutting edge meet is referred to as the "Mitsukado" (三ツ角) of the blade. This is a critical area that requires meticulous attention from the swordsmith or the Togishi, the craftsman responsible for polishing the sword.