Caligula is a clunky, yet sleek, jet-black revolver with a cylinder that holds five 0.50 caliber rounds inside. In Witch Hunter form, the armor is colored black and is described as being smooth and "simple" similar to its particular wielder's beliefs.
Caligula has yet to show any personalities of their own. However, it is noted that all of Caligula's previous owners were never "right in the head". Like other Relic Eaters, Caligula seeks an attribute from its wielder and its chosen attribute is life, for which Kurogane was constantly able to provide. It is stated that Caligula does not simply "trust" Kurogane but has sworn its allegiance to him and to him alone. Vlad has mentioned that Caligula possesses a female persona.
Caligula was handed down to Kurogane during the day he was assigned to the EXE and has been with him ever since.
Witches Struggle Arc Edit
Caligula is first seen being used when Haunted shows himself inside the mock-battle coliseum and Kurogane intercepts the thorn tentacles with multiple shots. However, Haunted is able to do enough collateral damage to shift Kurogane's attentions elsewhere while he evades fighting the rest of the Dullahans by constructing a complex barrier between them. Caligula's Witch Hunter mode is activated by Kurogane to swiftly deal with the hijacked dragoons.
Hyakki Yakou Arc Edit
Kurogane stops the short duel between Takeru and Kyouya to capture the former along with Kiseki while punishing Kyouya with a shot in the shoulder for disobeying orders. He leads the convoy with Kiseki in holding to transport her to her new containment facility, only to have Valhalla attempt to take her away. Kurogane and Kyouya fight off 3 Einherjars until Orochi greets them and Kurogane orders for Kyouya to move on ahead without him as he planned on holding Orochi back as he pulls out Maximilian.
Witch Hunt War Arc Edit
With Kurogane's departure from the Inquisition, Caligula and Maximilian remained loyal to him despite Sougetsu's control over all Relic Eaters. Cailgula was primarily used the duel against Mamoru Jougasaki where Caligula's destructive power trumped Mamoru's Heliogabalus' defensive capabilities. Caligula was once again used to subdue Takeru where Kyouya assisted him in fighting Kurogane where he was forced to reload. Instead, Kurogane stopped Kyouya's attacks with his hand while pulled out Maximilian to counteract Takeru's offense. Kurogane accepts defeat and places his hopes onto the Heretic Alliance as he decides to stay behind and hold off the Hyakki Yakou cells spawning from the Guillotine users.
Relic Eater- Malleus Malificarum I: Taking the shape of a large revolver, Caligula is considered one of the most powerful Relic Eaters in terms of destructive power. Being one of earliest Relic Eaters, it is classified as a "test type" with Innocentius being the prototype, as it does not inherently have any anti-magical capabilities. What it lacks in countering against magic is made up for with its immense power. Caligula's requirements for its user is simple as it demanded vitality, an attribute Kurogane had an abundance of. It's sheer power is counter-balanced that it needed to be reloaded manually and could not be done until all of its 5 available shots were spent.
Intrinsic Magic- Tyrant: When a sufficient amount of life is taken, Caligula's power can be unleashed with the 5 bullets availble in its chamber. Kurogane can mediate how much power is used with each shot but even at its lowest output, Caligula's gunfire had the power comparable that of a cannon or a tank. In higher tiers of power output, Caligula's magic shot out heavy black lightning. This magical output was great enough for Lapis to be unable to properly absorb its power.
- Tyrant Enchant: A physical enchantment where black lightning coats the user's physical attacks instead of enchanting its bullets.
Witch Hunter Armor: Caligula grants its user with a lustrous, form fitting black armor that increases Kurogane's already impressive physical capabilities. The level of physical protection the armor gives seems to proportional to the strength augmentations as Kurogane favored physical combat with the armor on. The black armor is also frequently used in conjunction with Maximilian's magic
- Following the trend of Relic Eater namesakes, Caligula is named after the nickname of the 3rd Roman Emperor of the Julio-Claudian Dynasty. He was most notable for his descent into absolute madness and tyranny that ended with his assassination by his own guards.