Regulus Corneas had a plain and unremarkable face, with golden eyes that often appeared dull and disinterested, though they would glimmer with intensity whenever he launched into his long, self-righteous speeches. His features were modestly handsome, not particularly striking or unattractive, and his hair, naturally white despite his youthful appearance, lacked any distinct style or length. His pale, untanned skin and all-white hair and clothing gave him an almost ghostly presence, as though every trace of color had been drained from his body, making him appear both pure and unnervingly lifeless.

His usual outfit consisted of a pure white greca-style overcoat that reached down to his ankles, adorned with gold-edged cuffs, a row of five golden buttons down the front, and golden trim. The inside of the coat was black with vertical golden stripes running throughout, and the high-neck collar decorated with an infinity symbol hinted at the eternal nature of his Authority. Beneath the coat, he wore a deep blue dress shirt, white trousers, and matching white shoes. A single deep blue teardrop-shaped earring hung from his right ear, attached by a thin gold chain that matched the color of his shirt.

During the mock wedding he attempted with Emilia in Arc 5, Regulus changed into a more formal attire: a white tuxedo with a cape-like tail that flowed down nearly to his heels. The outfit kept his signature white palette but added elegance, featuring a blue and white striped undershirt, a black and gold striped ribbon, white gloves, and polished white shoes, all emphasizing his obsession with purity, perfection, and control.

Regulus was extremely talkative and often described himself as unselfish, despite being the embodiment of Greed. He had a tendency to ramble endlessly about trivial topics in incoherent and self-centered ways, confusing those around him with his warped ideals and contradictions. His prideful personality drove him to impose his own twisted sense of logic on others, forcing them to accept his beliefs as truth. Whenever someone challenged his views, he would become irrationally angry, accusing them of “violating his rights” before attacking or killing them without hesitation. Although he often claimed to be pacifistic, he showed no restraint in harming or murdering others if he believed his so-called rights had been infringed. Regulus demonstrated no understanding or respect for others’ feelings or values and constantly acted in ways that revealed his hypocrisy and sociopathic tendencies. His outrage toward Rem for merely preparing to defend herself after he had just massacred dozens of wounded soldiers perfectly captured his delusional and self-righteous mindset.

He viewed himself as a divine being and often called himself “the most satisfied existence in the world.” His arrogance blinded him to the strength or worth of others, even mocking powerful individuals such as Reinhard van Astrea, whom he dismissively referred to as “some guy who knows nothing but swinging a sword.” Regulus frequently expressed his desire to be left alone, claiming he disliked interacting with others, yet he had no issue engaging in conversation until someone “violated his rights,” which would trigger his violent temper. His lack of emotional growth over more than a century as a Sin Archbishop, during which he was never once seriously threatened, left him intellectually and morally stagnant. When Subaru finally exposed the truth of his Authority, Reinhard was able to end his life. Even in his dying moments, Regulus remained arrogant and delusional, proclaiming hatred for anyone who looked down on him and admitting he became a Sin Archbishop only to protect himself from ridicule. His final screams were filled with hatred for humanity itself, wishing for the complete erasure of mankind.

From birth, Regulus possessed a distorted and corrupt mindset that rendered him incapable of understanding love, kindness, or empathy. He perceived any show of compassion or pity as mockery, twisting it into justification for violence. Lacking all emotional depth, he grew increasingly paranoid and detached from reality, convinced that everyone despised him. After inheriting the Witch Factor of Greed, he succumbed fully to his delusions, destroying anything that challenged his fragile worldview. He built his life around the fantasy of a perfect kingdom where he ruled supreme, surrounded by “wives” who existed only to affirm his superiority. For a century, Regulus lived in denial of his greed and cruelty, until his death beneath the streets of Priestella marked the collapse of the illusion he had desperately clung to, a self-made god undone by his own emptiness.

Regulus Corneas possessed the Authority of Greed, which was divided into two devastating abilities: Lion’s Heart and Little King. With Lion’s Heart, Regulus could completely stop the time of his own body or anything he touched, rendering himself invincible and immune to all physical phenomena such as aging, hunger, or damage. Anything affected by this power ignored the natural laws of the world, including gravity, resistance, and even momentum, allowing Regulus to walk through solid matter, bypass any defense, and turn simple objects into lethal weapons. He could apply this ability to air, earth, water, or even his breath, creating invisible traps and high-speed projectiles capable of shredding opponents or annihilating entire convoys. Using Lion’s Heart on the ground allowed him to walk or launch debris like bullets, while on water it enabled him to walk across surfaces or generate devastating tidal waves. However, the immense power came with a severe limitation, as his heart stopped beating whenever he used Lion’s Heart, restricting him to a few seconds of invulnerability before suffering excruciating pain.

To counter this, Regulus used his second ability, Little King, which shared his heart’s function with his wives. By connecting pseudo-hearts to each of them, he could sustain his own lifeless state indefinitely, maintaining his invincibility as long as their hearts continued to beat. This ability effectively made Regulus immortal and unstoppable unless his wives were incapacitated or killed. If their hearts stopped or if the pseudo-hearts were destroyed, his Authority would collapse, leaving him vulnerable. The range of this link was uncertain, but it depended on his ability to feel their presence or “love.” Alongside his Authorities, Regulus wielded a Gospel, a black book that revealed fragments of the future to its owner, and a Conversation Mirror, a meteorite artifact that allowed him to communicate with others holding similar mirrors. Together, these powers and tools made Regulus one of the most dangerous and invincible beings in the world until his defeat at the hands of Subaru, Emilia, and Reinhard.

More than a century ago, Regulus lived in a small village outside the Four Great Nations. After being chosen as the Sin Archbishop of Greed and obtaining the Witch Factor, he slaughtered his family, his village, a nearby town, and eventually his entire country. He broke the mind of his childhood love, killed her family, and forced her to marry him before she took her own life. Regulus buried her and began taking numerous wives, forcing them to remain emotionless.

He later obtained a black box similar to Petelgeuse’s, possibly containing a Witch Factor. As the leader of the Witch Cult’s radical faction, he occasionally cooperated with Petelgeuse of the moderate faction while continuing his pattern of kidnapping and killing his wives.

A hundred years before the main story, Regulus attacked the elven village in Elior Forest with Pandora, attempting to claim Fortuna as his 79th wife. He nearly killed Petelgeuse before Pandora erased his actions and sent him away.

Years later, Regulus destroyed the fortified Vollachian city of Garkla and killed thousands, including the hero Kurgan, solidifying his reputation as one of the most powerful Sin Archbishops.