Grutrissheit

Grutrissheit (グルトリスハイト, Gurutorisuhaito) is the name of the book held by Mestionora. According to legend it is the original bible that the first king of the country was permitted to transcribe upon being chosen by the Gods.

Presumably all other Bibles have been copied from this transcription by the first king.

Spoiler for Part 4 Volume 6 The statue of Mestionora in the library holds Grutrissheit in its hands, which Rozemyne filled with her mana at the request of Schwartz and Weiss.