Black Beast

A Black Beast ( 黒き獣くろきけもの ) is a being of unimaginable power that lusts for the destruction of everything it contacts. Numerous Beasts have existed in the world's history, but the most famous of which was one that existed during the Dark War.

Information
Black Beasts have two known origins - the imperfect fusion of an Azure Grimoire with a Boundary Interface Prime Field Device or as a primordial and malevolent being that exists within the Boundary.

The earliest known appearance of a Black Beast was before recorded history. Lulled by the Azure Shrine Maiden, it emerged from a cauldron within Wadatsumi, Japan. Before it could harm the world, the Maiden lured it back into the Boundary, sacrificing herself to prevent calamity. This land was later protected by her descendants, the Amanohokosaka Clan, for millennia.

When humanity had enough of the Prime Field War, they created a Black Beast to ensure their victory in the pursuit of the Azure. They could use the Takamagahara System to rewind time after having claimed the Azure, reversing the damage and even birth of the Beast. This plan never came to fruition, however, as The Origin used the Amaterasu Unit to create a new world.

On December 31st, 2099AD, a Black Beast appeared, having fallen into a cauldron in 2199AD and being sent back in time - this Beast was created by the fusion of Nu-13 and Ragna the Bloodedge and is the most infamous of all the Beasts to have appeared. It destroyed Japan before making its way across Eurasia, beginning the Dark War. This long and bloody war lasted for over 10 years before the Six Heroes finally defeated it. This Black Beast destroyed the world's ecosystem and over half of the world's population, radically changing the world around it. Ars Magus, the Novus Orbis Librarium, Nox Nyctores', Hierarchical Cities, and much more all came into being because of the Black Beast. It was personally slain by Hakumen with the Interfectum Malus: Ookami.

Black Beasts lust after the destruction of everything that they come across. They are not senseless, however, and are extremely smart, being capable of battle tactics and learning from their encounters. Their bodies endlessly spew seithr, and wherever seithr is, a Black Beast can teleport to, generating a circle similar to that seen in sorcery. What makes a Beast truly terrifying, however, is that it exists outside of Logic, making it impervious to nearly anything that is not an Art. It has an incredible physical strength that can destroy anything it contacts, and has both a seemingly infinite amount of stamina and a limitless threshold for pain.

Wherever a Black Beast appears, there exists the probability of a  appearing from that location in the future. Remnants are not as powerful as the Beast but are still powerful enough to effortlessly defeat Jubei and Ragna when neither were equipped with appropriate weapons.

The appearance of Black Beasts are simple. They are creatures that tower above cities, have eight serpentine heads filled with rows of sharp teeth, and bodies that are pure black with red lines. Their main bodies are masses of seithr with numerous tentacles protruding from underneath.

BlazBlue: Central Fiction Library Entry
''January, 2100. The dark creature appeared out of nowhere right on top of Japan. In reality, it was a high concentration of seithr, but its outwardly appearance earns itself the name, the Black Beast.''
 * Black Beast

''The world leaders of the time launch an all-out nuclear strike against the Black Beast. The strike, however, only destroyed Japan as we know it, without scratching the creature. After the destruction of Japan, the creature moved towards Eurasia, destroying everything in its wake.;;

''Everywhere that there was seithr, the monster could appear, and equally as quickly disappear. Mankind was at the mercy of this creature, until it suddenly stops for no apparent reason.''

''During that one year period, mankind develops what becomes known as Ars Magus to make a stand against the Beast. Around the same time, a group of six courageous warriors, known as the Six Heroes, successfully defeat the Beast in January of 2110.''

''The damage was done, however, and while the Beast was defeated, so was half of the world's population. Not only that, the seithr left behind from the Black Beast covered the planet, forcing people to live in Hierarchical Cities that are built atop mountains.''

''Genes extracted from the husk of the 'Black Beast' after it was defeated in the First War of Ars Magus. After many modifications and improvements, it's possible to use them to create artificial humans.''
 * Beast Genes