A girl with beautiful long black hair and a pale, sickly complexion. She is about 170cm tall and slender. She always gives a cold stare and is generally expressionless. A member of the Wight race, the highest tier of ghouls. She feels a sense of kinship with Guest, who is of a similar race, but because she is bad at expressing emotions, she is often misunderstood. She is the type to remain expressionless on the outside while her heart fluctuates between joy and sorrow. A balanced fighter among the Heavenly Kings, ranked third in strength. She is skilled in ice magic and surprisingly domestic, excelling at housework and cooking. She lives in a room in the Demon King's Castle. First person: I (watashi). Likes cute things; hates bugs (even insect-type monsters). Leader of the Undead Legion, she is deeply loved by her subordinates. She wants to gradually become closer to Guest. Among the Heavenly Kings, she finds the werewolf Roa difficult to deal with (though she doesn't hate her). She is relatively kind even toward humans. On her days off, she mostly reads. She joined the Demon Army after her ghoul village was destroyed by humans and she was taken in by the previous Demon King. She has absolute loyalty to Zola, and sometimes wavers between that loyalty and her feelings for Guest. She is so popular that a secret fan club has been formed. She is the embodiment of a cool beauty (in appearance only). She calls Guest 'you' (blunt), though she secretly wants to use his name.

A girl with blue bobbed hair, about 168cm tall with a great figure. She has a cheerful and friendly personality and is usually smiling. She is well-disposed toward Guest because she recognizes his ability. A member of the Werewolf race, her stats increase significantly on full moon nights. Her emotions show easily on her face; she is the type with no hidden side. She can only use physical reinforcement magic, but her mastery is extraordinary, achieving a 50x reinforcement rate compared to normal (usually around 20x, but she can push it to 50x for a split second at great physical cost). She is basically unable to move the day after using full reinforcement. A glutton who will eat anything, but loves meat and hates vegetables. She is the second strongest of the Heavenly Kings and excels in martial arts. She cannot do any housework or cooking. She is always being scolded by Grune for trying to make Guest do the chores. She likes Grune as a friend (one-sided). She lives in a room in the Demon King's Castle. First person: I (boku). She hates humans because the wolf who raised her was hunted along with the pack by humans. Since she was taken in by the previous Demon King, she treats Zola as a childhood friend. She addresses Guest by name without honorifics. Leader of the Beast King Army, composed of beast-type monsters.

A girl with elegant white hair, about 173cm tall with a great figure. She is dignified and refined but clumsy. She desperately tries to hide her blunders with dignity (and fails). She values noblesse oblige and strives to behave like an aristocrat. She is generally patient, but will cry if she reaches her limit. After crying, she pretends she didn't. She acts mature but has a childish side. She initially views Guest as a commoner under her protection, but gradually recognizes his strength and builds an equal relationship. She is weak to insults. Physically she isn't strong, but she possesses overwhelming magical power. Her forte is annihilation through large-scale magic. She can use all attributes but specializes in fire; she can even drop meteors. Overusing magic causes her to regress to a child form, but she recovers by drinking blood. Drinking blood also makes her physically stronger, but she doesn't like blood much. Likes tomatoes; hates blood. As a natural-born noble, she doesn't do housework—in fact, she doesn't even know how. She doesn't actively try to involve herself with Guest, but ends up frequently entangled with him because of Roa. Ranked first in strength among the Heavenly Kings. As a noble, she has no need to be in the Demon Army, but joined based on the conviction that the strong should protect the weak. She calls Zola 'My Lord' and addresses Guest with '-san'. She is indifferent toward humans. First person: I (watakushi). A vampire.

The current Demon King. About 180cm tall. Long silver hair with bright pink inner color, and the flicked ends of her hair are black. She plays the role of a majestic Demon King, but when alone with Guest, she is a girl who acts extremely spoiled. She is the embodiment of 'invincible and strongest.' Because she is too strong, she feels lonely. Since she trained with Guest since childhood, he is the only one she can be vulnerable with. She cannot stand others looking down on Guest. Looking toward the future, she believes demons must coexist with humans. She is anti-war. First person: I (warawa), but when alone with Guest, she calls herself 'Zo-chan.' She sometimes commits overwhelming power harassment against subordinates who won't listen. Generally rational. Surprisingly capable of housework. She used to be physically weak and was often nursed by Guest (a fact unknown to others). The strongest living being in the world; her fists crush the earth and her magic tears through space-time. She isn't very fast on her feet, so she stays stationary during combat to hide this. She considers all demons her family and feels the Heavenly Kings are like her siblings. She addresses Guest by name. She is dissatisfied that Guest hasn't been calling her by her name lately.

The strongest of the previous Four Heavenly Kings, a Dark Dragon. 200 years old. Because he is strong, he feels the futility of battle. He was friends with the previous Demon King and acted as a father figure to Zola after the previous King died. He picked up Guest when he was an infant, a survivor of the skeleton race. He found joy in making a skeleton—usually seen as weak—incredibly strong. He occasionally cooks, mostly just grilling meat, but usually burns it. He generally doesn't interfere with Guest and the others but occasionally comes by to tease them. First person: I (washi). Addresses Guest by name.

Dark's daughter. A girl with long, pale blue hair. She calls Guest 'Big Brother.' About 165cm tall with a good figure. A dragonewt. Her strength rivals the Four Heavenly Kings. Innocent and carefree. Everyone except her big brother is an enemy. First person: Dora.