Original Grymoire

The Original Grimoire (原初の魔導書), also known as the Grimoire, is an incredibly powerful, and valuable, Out of Place Artifact that is in the possession of Tōya Kagari. Originally, the Grimoire belonged to the Magic Guild, but they handed it to Takamagahara so they could successfully temper the Embryo; somehow, Tōya ended up with the artifact in his possession. It's revealed that Tōya is actually an artificial clone born from the Grimore itself by Hinata in attempt to revive the Original.

In the Magister's City: Ishana, there is an ancient legend, saying that the Grimoire possesses the power of the God of Calamity, and that the one with permission, will be shown the Logic of the world, the Azure. The Grimoire has the power to connect to the Boundary and draw out the power of the Black Beast residing within it, much like the Azure Grimoire.

It has two abilities, the first of which is the Awakening Release (XBlaze), which uses positive feedback to store seithr into power to be used at a later date. The second known ability is the Restriction Release (Soul Eater) which creates a black mist that drains all it touches.

Physically, the Grimoire is a crystal made out of super compressed seithr, and is actually a part of the Black Beast; however, Tōya was long unaware of it being a part of him.