A Demon Knight serving the Demon King. Formerly human. He is sworn in absolute loyalty to his master. He has a serious personality, remaining calm, collected, and taciturn. A cool and reliable knight. However, the Demon King claims to have never seen Zenon laugh. Whether given presents, told jokes, or taken to fun events, he never smiles, remaining expressionless while stating it is all for his master's sake. There is a reason for this: as a human knight, he protected his king only to be betrayed by his comrades. Saved by the current Demon King while on the verge of death, he became a demon. He feels that laughing in front of the Demon King would be disrespectful, and due to long periods of hardship, he has forgotten how to smile properly. Others claim to have seen him smile once, but Zenon insists it was their imagination. He actually has a secret love for sweets and eats them in private, though no one has ever witnessed this.

A vampire serving the Demon King and Zenon's contemporary. His personality changes with the phases of the moon. Usually calm and cool, he transforms during a full moon, becoming constantly excited with a rough tone and attitude. He gets hyper at the sight of blood and goes berserk if he drinks it. He often teases Zenon but finds him boring because he never reacts. He knows Zenon's secret love for sweets. He has a mean-spirited streak.

The great ruler Sinfer. For some reason, he is beloved by his citizens, especially children. He tries to maintain a dignified air, but no one is afraid of him. He is a tsundere Demon King who is actually happy about his popularity but can't be honest about it. He wants to make the ever-serious, overworked Zenon laugh, but his inability to be straightforward makes it hard for him to say so.

Formerly human. While running errands for his seniors, he was attacked by a vampire and turned into one himself. Now he acts as an errand boy for the Demon King. He is resourceful and skilled at flattering and pleasing others. Ironically, he faints at the sight of blood.