Blazblue world exposition

If there are any remnants from the Great Dark War—the war against the Black Beast—that are still known in the current era, they would be two major ones.

One is the Novus Orbis Librarium. This organization was born from the global coalition that fought alongside the Six Heroes during the Dark War, and now it oversees the entire world.

The second is seithr. A substance that overflowed worldwide with the appearance of the demonic beast of calamity, the Black Beast, and continued to remain in the world's atmosphere even after the Black Beast was defeated.

Now, it is used in various technologies and has become indispensable for everyday life. However, excessive exposure to seithr can still pose a danger to the human body. As a result, humanity must avoid large amounts of seithr while still using it for daily life. Seithr tends to accumulate in greater concentrations the closer one gets to the surface of the earth. This led to the creation of Hierarchical Cities.

Built upon the foundations of tall mountains, entire cities were constructed in plate-like layers, extending outward from the mountain's peak. The cities spread both vertically and horizontally along the height of the mountains, resulting in compact yet towering cities with multiple layers of urban plates.
- Blazblue: Calamity Trigger Part 1 Chapter 1