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Anguis Inférnis: Leviathan

Owner: Yami Akuhei
Previous Owner: Akuhei Yamaorochi
Name: Anguis Infernis: Leviathan
Translation: The Netherworld Serpent, Leviathan
Form: A seperated blade that also transforms itself into a chain
Manifested Snakes
Energy Source: Seithr
Magic from the Boundary
Soul Energy
Type: Nex Exitium

Anguis Infernis: Leviathan is one of the original Exitium, which never had its core properly sealed, giving it an insatiable desire to consume to grow in power. Yami Akuhei uses it during Control Sequence.


Leviathan is one of the Extitium created in the past. The magic that made it is said to not have been capable of making with the technology known back then. Once belonging to the terror people referred to as the "Unholy God Serpent", it was recovered by Lukain to later be given to its new owner, Yami Akuhei.

It's a blade of multiple separated bits that break apart and designs itself into a chain. The smaller protruding blades on its body are easily detached, becoming useful as knives to its wielder.

According to Akuhei, it's not at its full strength.


Created during the Third War, Leviathan was crafted with the efforts of magic and technology said to be beyond mankind's known knowledge. Yamaorochi designed it and Ophius on his own based on data the NOS had, and it was the only Exitium that grew beyond control, becoming nearly unstoppable at the height of the Third War.

Leviathan experienced an unknown weakness that cost its owner during the time of the World Irregularity Crisis, allowing the Rogue Sectors to eventually defeat it and Yamaorochi. Despite this, they weren't able to destroy the weapon's core. The NOS eventually came to recover Leviathan from the enemy, and the weapon was given to Lukain.

Lukain would hold onto the weapon until entrusting it to Yami Akuhei. Leviathan was then immediately put under restraint by the Council's order, where the system monitors its power and they utilize it as a means to counter the powers threatening their world, such as Nex and his Grimoire. Leviathan is currently directly linked to the system's power that restrains it and this power, Akuhei has hinted is beyond even Nex's Grimoire.

Leviathan was also a primary reason to the choice to now restrain and seal the Exitium's cores, in order to avoid them becoming threats.

Powers and abilitiesEdit

Leviathan's will is almost impossible to restrain by the NOS. The numerous souls it has taken into its body have given it a power in magic beyond most, granting its wielder inhuman-levels of strength that is said to originate in the Boundary.

Like all Exitium, it can destroy existence by corroding the life force in a soul, before reducing them to Seithr and sealing them in a void. Leviathan's magic is potent enough alongside its wielder's vicious desires and will to completely corrupt and kill the victim without much resistance. Leviathan doesn't only erase the victim, but it consumes their energy into its core which it would use to empower its wielder. However, it can't use the energy without the system's permission.

It can generate Seithr in its core, eliminating the need to take in any around it. The energy it generates turns into shadowy emerald snakes that are composed of Seithr and magic, a manifestation of Leviathan's power when taping into the Boundary. When the weapon sticks into an individual, it releases green, glowing serpentine veins that drain their natural energy weakening them significantly. This has been used on both Nex and Hiro, Nex's abilities were drastically reduced, and Hiro was unable to counter Akuhei with Clarity.

The attacks delivered drain enemy of life and energy, in an odd similarity to Soul Eater. These effects are known to be worse than overexposure or Seithr Scourge.

Nex has hinted Leviathan has a certain lasting effect on the minds and psyche of its victims.


As a Blade: As a sword, Leviathan takes shape of a semi-long black and neon-green blade with sawtooth edges. In this state, the blade's body is broken up into sections and attached loosely only by a green chain-like aura running through the center. On the edges of each section of the sword's blade are small and detachable protruding blades which grind enemies. Its grip is a continuation of the serpentine spear-head, with coils on the guard of the weapon. The pommel and handle make up the snake's head with two fangs folded in, with the tail being the very last point of the blade.

As a Chain: Aesthetically, the veins and emerald highlights adorning the blade remain while in a chain shape. Its blade breaks apart, extending by the aura between each piece making up the sword's body. This aura allows it to be manipulated to curve and bend freely. Leviathan's smaller blades extend and become angular, floating just off it by force of magic. The snake's eyes light up in this state with a green glow, and the fangs in its mouth are visible. As a chain, it has no end, being summoned from a magic dark void, but the point of the sword becomes the tail of the serpent. When called on, the chain can also bathe itself in shadowy energies to shape vicious serpents that attack Akuhei's enemies.

Upon returning to a sword shape, the gaps between the blade's body close and the smaller saw-tooth blades return to their usual position.


  • The name translates to the Netherworld/Underworld Serpent or The Snake of the Underworld, and could be considered the same as its owner's alias.
  • It's name represents the Leviathan, which is a serpent of the Abyss, or Dragon of the Sea in mythology.  
  • The snakes summoned by Akuhei are actually created by Leviathan's magic.