All known history of this world begins with the "Great Obliteration" of the Ancient Era.
If the "Great Obliteration" is viewed as a wall, then this invisible barrier is clearly more than just a simple "event node"; it factually "cut off" the entire historical timeline.
All that predates the Great Obliteration is unknown. Archaeologists have exhausted all their wisdom and effort, but are unable to recover even a trace of information from before that time point; one cannot even find any historical relics pointing to the period before the Great Obliteration—not even a stone fragment etched with characters.
This "black wall" of despair has stood in the eyes of scholars for ten thousand years, and now Captain Duncan Ebnomal, who returned from Subspace, has given this barrier an apt name.
As the leader of the Academy of Truth, the Pontiff of the God of Wisdom, Rune felt the presence of that black wall and the subtlety of the "limit of vision" more deeply than anyone else.
