TV-Series
Description
Caliburn is a Demon Sword and the familiar of Arthur A. Angel, the Paladin of the True Cross Order. This sentient weapon is stored in a sheath on the front of Arthur's belt. In terms of its physical form, Caliburn is a large, heavy broadsword whose blade has a flat, sharp tip resembling a guillotine rather than a traditional point. The most distinctive feature of its appearance is the golden pommel at the end of the hilt, which displays a face that is capable of speaking without moving its mouth.

Caliburn is characterized by an intense, almost obsessive devotion to its master, Arthur. Its personality is flamboyant in nature, and it is almost single-mindedly focused on the Paladin, to the extent that its hobby is described as thinking about Arthur and its favorite words are everything Arthur says. Its favorite pastime is defeating demons alongside its wielder. This devotion forms the core of its identity and drives all of its actions.

The sword was originally kept in the depths of the Vatican Main Office, where it remained stuck in a mysterious pedestal. Arthur A. Angel, desiring a reward for his work, successfully made a contract with Caliburn and pulled it from the pedestal, and the pair have worked together for a long time since that event. The contract between them is significant, as Arthur's own body serves as the price for the bond.

In the narrative, Caliburn first appears alongside Arthur when the Paladin attempts to execute Rin Okumura. Later, during an incident in Yemen involving a powerful demon known as the Impure Princess, Arthur asks Caliburn to lend him its power. Caliburn responds by stating that to defeat the Princess, it would require a sacrifice of at least Arthur's hair. Arthur gladly gives this offering, allowing them to launch a devastating attack that destroys the Impure Princess's castle form in a single blow. This demonstrates the nature of their relationship, where Arthur must pay a personal price to unlock Caliburn's full potential.

Caliburn's primary role in the story is that of a weapon and partner to the Paladin, Arthur A. Angel, serving as his primary means of combat against powerful demons. Its key relationship is exclusively with Arthur, to whom it is utterly devoted. There is no indication of significant relationships with any other characters; its entire existence is focused on the Paladin.

While Caliburn itself seems incapable of moving on its own, it grants its wielder access to powerful techniques. The most notable of these is the Angel Slash. To perform this attack, Arthur cuts a lock of his own hair with Caliburn, after which he swings the Demon Sword to create a destructive wave of energy. This technique is shown to be overwhelmingly powerful, capable of completely destroying a demon of the Impure Princess's magnitude in a single hit. Caliburn's favorite food is explicitly stated to be Arthur's hair, which explains why cutting it serves as a sufficient sacrifice for the Angel Slash technique.