Prologue・Introduction

—A.D. 2100.
Mankind faces a trial they have never foreseen.

The "Black Beast," suddenly appears in Japan to wreak havoc. To combat its disastrous powers, countries from all over the world fired nuclear weapons toward the already devastated Japan. However, even the combined forces of nuclear weapons were no match against the Beast, as it advanced into the Euro-Asia continent. This era would soon be known as the "Dark War"--the greatest war in the history of mankind.

Humans were powerless against the Beast: no matter how advanced or destructive the weapon, they were far from defeating the Beast. People began to live in fear of the Beast, as it continued to terrorize the world over.
But everything changed when the "Six Heroes" arrived.

Thanks to the Great Magister Nine and her creation, the "Ars Magus," humanity finally obtained a means to combat the Black Beast. The humans and the Six Heroes joined forces, and succeeded in defeating the Black Beast after 10 years since its initial appearance in Japan.

However, even with the Dark Beast dead, the war left a deep wound in the world. In order to escape the hazardous element known as "Seithr" that the Black Beast's carcass emanated, humans were forced to live in Hierarchical City: an isolated civilization located in high altitude, where Seithr concentration were low.

It is now A.D.2199.
In the 13th Hierarchical City, "Kagutsuchi," under the control of Nobus Orbis Librarium, a man named Ragna the Bloodedge appears. He is a man with a SS rank bounty on his head, who rebels against the Librarium with his Azure Grimoire in his right hand.

When he awakens, the man remembers nothing.

Not knowing where he is, or who he is, the man wanders into the 13th Hierarchical City, Kagutsuchi, as if to be guided by something.

All he knows, is that he is labeled a rebel of the Librarium: the "Grim Reaper"...
And that he holds the "Azure Grimoire"...
And certainly, he is targeted by the Librarium...

The man, with a sort of nostalgia, heads deeper into Kagutsuchi: toward the deepest part of the city, known as the "cauldrum."

Is this a mere walk down memory lane, or a "Central Fiction,"--