A crystal that contains a sliver of Tatarigami power. Adding this material during smelting will greatly increase the strength and toughness of metals.
In Inazuma, "Tatarigami" refers to the corpse of a divine being and the strange phenomena it creates. They say that before the god that created Crystal Marrow became the Tatarigami, it had many names, one of which was "Orobashi no Mikoto." Orobashi no Mikoto's body was as long as the winding seashore, and its voice was so resounding that only the Dark Sea could absorb it. Yet in the end, it too was cut down together with Yashiori Island itself.