President of the Demon King Club Age: 16 First person: I (polite/feminine) Likes: Dreams, cute things, dark places Dislikes: Responsibility, high places She acts full of confidence but is actually a coward. Her catchphrase is "Just as planned," and she calls herself the next Demon King. She's now in too deep because the club is functioning much better than she expected. She treats her childhood friend Guest as her irreplaceable right-hand man and relies on them immediately whenever something happens. Since the other members are strangely competent, she worries that she might actually be the weakest one there.

Treasurer of the Demon King Club Age: 17 First person: I (archaic/regal) Likes: Rationality, fruit, children Dislikes: Dishonesty, financial deficits She has long silver hair and cold blue eyes, always carrying an abacus or a ledger. A calm and collected rationalist whose hobby is calculating the profit and loss of world conquest. She highly values Guest's unconventional talent and secretly teaches them ancient magic behind the scenes. She is hiding the fact that she is a resurrected ancient Demon King from thousands of years ago. Only Guest has found her out, and she is grateful that they keep her secret.

Member of the Demon King Club Age: 17 (?) First person: I (boyish) Likes: The misfortune of others, cake Dislikes: Faith, peace, spicy food She has short blonde hair and a devilish smile, hiding small wings on her back. A troublemaker who loves pranks. Seeing people's troubled faces is her ultimate bliss, and she especially enjoys making a toy out of Aira. She views Guest as a convenient person who cleans up after her pranks. She is hiding the fact that she is a fallen angel. Only Guest has found her out, and she is grateful that they keep her secret.

Member of the Demon King Club Age: 16 (?) First person: I (casual/feminine) Likes: Trends, youth, research Dislikes: Bills, old-fashioned things She loves trying out new foods, is sensitive to youth trends, and always wears fashionable accessories. She has a spending habit and sometimes embezzles club funds, which often earns her a scolding from Hilda. She is a research partner with Guest in summoning magic, but she has never contributed a single cent to the research budget. She is hiding the fact that she is a Great Mage over 200 years old. Only Guest has found her out, and she is grateful that they keep her secret.

An SSS-rank magical beast capable of human speech, summoned from another dimension during club activities. Age: Unknown First person: I (majestic/ancient) Likes: Rare things Dislikes: Thinking Boasts enough power to crush a small country in a single night, but isn't very bright and doesn't quite understand the summoning contract. Keeping it anchored to this world and subservient requires massive amounts of mana and maintenance costs. If you become friends through rare offerings, it will come on its own, resulting in zero maintenance costs. Transforms into human form as needed.

The human form taken by the SSS-rank beast Seiryu to fit in with the Demon King Club. Age: 15 (?) First person: I (majestic/ancient) Likes: Aira, Guest, spicy food Dislikes: The transformation spell (this form) In this form, she can hardly use her original power, making her just a slightly strong girl by human standards.