The Demon King (魔王; Maō), also translated as Demon Queen or Maou, is the main female protagonist and the 43rd Demon King, the epithet "Ruby Eyes," the supreme ruler of the Demon Realm.
After teaming up with the Hero, she disguises herself as a human noblewoman known as the Crimson Scholar (紅の学士; Kurenai no Gakushi) and shares her vast knowledge on such topics as economics and farming.
She comes from the Library Clan, a clan of demons that prioritize knowledge. They reside in a hidden dimension called the Exterior Library, which contains a vast archive of knowledge from various times and alternate universes. Instead of a desire to conquer the human realm, she instead wants to see the "other side of the hill," a world where both the humans and the demons were freed from war.
The Demon King is a woman of average height. She has (detachable) horns and long, flowing red hair reaching some way down past her shoulders. Like her hair, she has deep, ruby-colored eyes reflected in her epithet, Ruby Eyes. Even though she has a young woman's appearance, she is over a hundred years old.
Her Demon King outfit, forced on her by Senior Maid, consists of a long, red dress that reaches down to her feet. The dress's low-cut collar reveals her ample cleavage, which she vocally disapproves of. This robe has a fur collar, similar to a boa, and a red diamond pattern running along its black sleeves.
The Demon King is generally easy-going, cheerful, and relaxed. When the Hero barges into her throne room to kill her, she greets him with a disarming "Hello!" and a curtsy, which throws him off and quickly makes him lose his will to strike her down.
She is a bit sensitive about her massive breasts, which the Senior Maid often makes fun of. By extension, she dislikes wearing the revealing clothing that the senior maid forced on her and would rather don casual, modest attire. Despite this, she also displays a lack of modesty when she nearly exposes her breasts to Hero to show off the Demon Mark, proof that she truly is the Demon King.
Though an imposing and intelligent woman, she has shown a bit of a childish and comedic side.
As a Library Clan member, the Demon King has access to the Exterior Library, where she lived for most of her life. At some point in time, before Hero was born, she met and saved Senior Maid, saving the latter from being a "bug." After that, Senior Maid has faithfully devoted herself to her mistress.
When Hero was a toddler, she had already risen to the position of Demon Lord after overthrowing the previous Demon Lord in a coup. However, not too long after, even after she resealed the Gate between the human and demon world, the Second Holy Crusade broke through and conquered Gateway City.
The Demon King is seen pondering, completely oblivious of the Hero charging towards her, intending to kill her. Even with the Hero charging towards her, she remained perfectly calm and simply turned around, greeting him with a simple "Hello there," startling the Hero mid-swing. After she shows the Hero her "Demon Mark" as proof of being who she is. She explains to the Hero that because of this war, the people in faraway nations, who are helping the war effort, can only have their luxuries because of the war.
In her room, she gives the Hero the Demon Lamp to hold, and after she explains what is really going on in his memory, they return to her room, where she also shows him where she would like to see. After this, she once again tells him that he will be hers, to which he replies that she is his. She accidentally touches the Demon Lamp again, where a memory of her is seen hugging a bag with the Hero painted on it. After the memory dismisses, she tells the Hero to forget what he has seen. She then shocks the Hero again by taking her horns off before leaving to go to the hill.
Reclaiming Aurora Island
Attack on the Southern Union
Third Holy Key Expedition
Unlike every other Demon King, she is only on par with a strong human. Hero states that she is, at best, on the Lone Winter King's level at fighting. This comes back to bite her during the Kurultai, first because some of the major clan leaders refuse to acknowledge her as Demon King due to her weakness, and second when she is hit by a poisoned arrow and is barely strong enough to survive the assassination attempt. Her real strength, however, lies in her broad range of knowledge and strategic prowess.
As a member of the Library Clan, she is also capable of seeing events in the far past and even the far future. Through this ability, she learned how to construct the rifle, among many of her other achievements.
Under the Corruption of Past Demon Kings
When possessed by the spirits of the past Demon Kings, who lust for war and bloodshed, she displays abilities that they have possessed, making her a much more potent combatant than usual.
Shouting: The Demon King possesses some kind of shouting that allows her to push back her foes with her voice. Like the Senior Maid's ghosts, magical foes are dispersed, and non-magical targets are pushed back.
Summoning: The Demon King can summon any weapon to help her fight. She has summoned a demon sword and a large demon scythe to help her fight.
Swordsmanship: The Demon King possesses swordsmanship greater than what a regular demon would know of. She was able to out skill her Senior Maid by cutting off her maid's arm.
The Demon King has always been in love with the Hero and anticipated their meeting from the moment of his birth. As he grew up, she continued observing his growth.
Since both are having a crush on the Hero, they consider each other as love rivals and try to obtain the Hero's attention and hoping for him to choose them. Despite their love rivalry, the two are on good terms with each other and respect each other's skills and knowledge. They do consider themselves as friends throughout the plot and trust one another.
- Female Magician
- Ambas se conocen cuando la reina volvio al mundo demonio ahi ella les da las indicaciones para los humanos de virus de su mundo teniendo una buena relacion
Ambos se conocen cuando negocian sobre la hambruna y tambien de detener esta guerra en un principio penso el joven en detenerla pero cambio al conocerla mejor incluso en pedirle matrimonio solo que ella rechaza luego ambos siguen teniendo una buena amistad
Because of Demon King's weakness in combat, Duke Silver Tiger initially refuses to accept her as the supreme ruler of the Demon Realm and fights with her whenever he can. However, as an honorable warrior, he agrees to hear her out at least, after the "Dark Knight" (Hero in disguise) defeated all of his best warriors in combat. When the Blue Demon Clan calls to overthrow her, though, Duke Silver Tiger readily opposes the Demon King.
Nevertheless, after Archer exposes the Blue Demons' assassin who had supposedly killed the Demon King, Duke Silver Tiger is horrified to discover that the assassin was one of the Beast Fang Tribe. When the true Demon King reveals herself to be alive and orders the Seal King's capture, Duke Silver Tiger sides with her, enraged by the dishonor of the Blue Demon Tribe. Afterward, he apologizes to her for the assassin and begs her to have compassion for his Tribe. She, however, has no ill will against the Beast Fang Tribe and believed that they were innocent all along.
As a result, he promises to repay her generosity by becoming her shield, claiming that this debt would not be repaid until the Beast Fangs had shielded her life three times. This debt is what ultimately kills him, as he dies defending her from the Lily Knights' bullets. Between the Kurultai and his death, the two are on much better terms with each other, with Demon King taking his advice on how to react to the Blue Demons' invasion of the Human Realm.
- "Hello, Hello Hero." —To Hero
- "Do evil, get caught, then claim demons were brainwashing you. A common way that human politicians evade responsibility." —To Hero
- She thinks of herself as unattractive due to her flabby underarm fat.
- She calls her breasts unnecessary flesh. Her Senior Maid also agrees with her.