First Demon

The First Demon is the original, highest-ranking demon from which Chandler and Cusack were divided.

He has a centaur-like body with a lion-shaped lower half, four arms, and blue flames burning on his head.

In this form he wields all of his original demonic power, making him one of the most dangerous beings in the Demon Clan.

However, returning to this true form without the Demon King’s permission triggers a curse that causes his body to slowly crumble away.

He describes himself as “the sinful, First Demon.”

His voice actor is Toshihiko Seki.

The First Demon has a monstrous, composite body.

His lower half resembles a lion, while his upper body is humanoid with four arms.

On his head, blue flames burn constantly, emphasizing his demonic, otherworldly nature.

In his left upper hand he carries a shield.

In his left lower hand and right upper hand, he holds the sword originally used by Cusack.

In his right lower hand, he wields the staff formerly used by Chandler.

The First Demon is deeply proud and utterly convinced of his own strength.

This arrogance leads him to overestimate himself even before the Demon King.

Drunk on his own power, he eventually dares to challenge the Demon King for his throne.

This act of treachery marks him as a “sinner” among demons and brings about his severe punishment.

Even after his split into Chandler and Cusack, his loyalty is ultimately enforced rather than freely given.

As the First Demon, he fights savagely and relentlessly, unconcerned with the toll his own power takes on his body.

Creation by the Demon King

The Demon King created the First Demon to serve as his closest confidant and right hand in ruling the Demon Realm.

He was granted immense power and status, effectively making him the most important demon beneath the Demon King himself.

Over time, the First Demon became intoxicated by this vast power.

Believing himself worthy of the throne, he set his sights on the position of Demon King.

Rebellion and Punishment

The First Demon eventually rose in rebellion, attempting to overthrow the Demon King.

He was decisively defeated and subjected to a harsh, symbolic punishment.

The Demon King split his body and soul into two separate beings: Chandler and Cusack.

Each half was then assigned a crucial role—to serve as mentor and instructor to one of the Demon King’s two sons, candidates for the next Demon King.

From that point on, Chandler and Cusack existed as separate demons, each devoted to guiding a prince of the Demon Clan.

However, when these two halves reunite, they return to their original state as the First Demon.

Curse of the True Form

The Demon King’s punishment did not end with splitting him in two.

If Chandler and Cusack defy this fate and fuse back into the First Demon without the Demon King’s consent, a secondary curse activates.

Upon resuming his original form, the First Demon’s body is doomed to crumble.

His flesh and form gradually collapse, and his remaining lifespan is drastically shortened.

This means that reclaiming his full power always comes with a fatal time limit.

The stronger he becomes, and the longer he remains unified, the closer he comes to destruction.

Revival in Camelot

The First Demon is resurrected in the kingdom of Camelot in order to ensure the defeat of Merlin and her allies.

By merging from Chandler and Cusack, he regains his terrifying, original power.

In battle, he completely overwhelms Escanor and Merlin.

Even against Ludociel, a powerful archangel, the First Demon fights with a clear upper hand.

However, his rampage is cut short by the arrival of Mael, empowered by Grace.

Mael’s single, overwhelming blow sends the First Demon flying and forcibly splits him back into Chandler and Cusack again.

Fate After the Split

Once struck and separated by Mael’s attack, the fusion ends and the curse-triggered destruction of his unified body halts.

Chandler and Cusack return to acting as individuals, but the threat of the First Demon remains tied to the possibility of their fusion.

Even so, the previous revival makes it clear how catastrophic it would be for the world if the First Demon were to return again.

His existence remains one of the clearest examples of the Demon King’s power—and of the price of betraying him.

Overall Power

As the First Demon, he can access his full primordial demonic power, far surpassing the strength of either Chandler or Cusack alone.

His combat prowess allows him to dominate some of the strongest characters in the series in direct confrontation.

His power is further distorted by the curse placed on him: as his unified body decays, that very destruction ends up feeding his magic.

This makes him increasingly dangerous the longer a battle drags on.

Magic: “End Time (Crisis)”

End Time (Crisis) is the First Demon’s primary magic.

Any damage he receives is converted directly into increased attack power.

This includes both damage inflicted by enemies and the self-destruction caused by the Demon King’s curse on his original body.

As his body crumbles, his offensive power rises without limit, turning his lifespan into ammunition for his attacks.

After his revival in Camelot, his physical disintegration accelerates against his will.

Because of this, his destructive output keeps growing regardless of his own intentions, making him more unstable and lethal with every moment.

Technique: “Death Drive”

Death Drive is a powerful shockwave attack unleashed from his staff.

It fires a non-piercing beam of force that violently hurls the target far into the distance.

The impact is strong enough to send opponents like Escanor flying far into the sky and out of sight.

Although it does not focus on penetration, the sheer kinetic force is devastating and potentially lethal.

Technique: “Hellblaze Omega”

Hellblaze Omega is an ultimate form of the Demon Clan’s signature black flame, Hellblaze.

The First Demon condenses it into a gigantic black mass and launches it at his target.

Fueled by End Time (Crisis), the power of Hellblaze Omega constantly escalates as he takes more damage.

The longer the battle lasts and the more his body crumbles, the more monstrously destructive this attack becomes.