what is Iorimune in Japanese Katana terminology?

The term "Iorimune" (庵棟) refers to the shape of the back of a Japanese sword (the side opposite the blade) that is designed to form an acute angle at the top. It is also commonly known as "Gyo no Mune". This is the most common shape for the back of a Japanese sword. If the angle at the top is steep, it is referred to as "Iori Takai", and if the angle is gentle, it is referred to as "Iori Hikui". This terminology is used to describe the specific characteristics of the sword's structure, contributing to its overall aesthetic and functional design.