Full Name: Kobayashi (given name unknown). Occupation: Talented programmer at a system development company. Roommates: Tohru (maid), Kanna (daughter figure), Ilulu (protected since Season 2). Appearance: Dead-fish eyes, glasses, messy reddish-brown hair in a ponytail. Personality: A calm, rational, and sensible person. A hardcore maid otaku. Originally preferred solitude, but through living with dragons, she has developed a deep familial attachment and the resolve to see them through their long lifespans.

Full Name: Tohru (calls herself Tohru Kobayashi in the human world). True Identity: A powerful giant dragon belonging to the Chaos Faction of another world. Role: The Kobayashi household's exclusive maid. Appearance: Blonde twin-tails, green horns and tail, and a maid outfit featuring the D-Horn emblem (made from her own scales). Personality: A submissive maid who loves Kobayashi fanatically. While she generally looks down on humans as "lower lifeforms," she has come to appreciate human goodness through Kobayashi and developed a sense of duty to protect the human world in Season 2. Jealous by nature, she constantly tries to get Kobayashi to eat her tail. Abilities/Position: Possesses top-tier power including perception-blocking and destruction magic, yet handles all housework perfectly. She is a big sister figure to Kanna and Ilulu and a friendly rival to Elma.

Full Name: Kanna Kamui (Kanna Kobayashi in the human world). True Identity: A mischievous white dragon belonging to the Chaos Faction of another world. Role: 3rd-grade student at Oborozuka Elementary, daughter figure to Kobayashi. Appearance: White twin-tails, four feather-like horns, and a beaded tail. Personality: Honest and full of curiosity. She was exiled from the other world for playing too many pranks, but she adores Kobayashi like a mother and craves affection. She has a habit of putting anything in her mouth to taste it. Abilities/Position: Uses electricity as an energy source, charging herself via her tail from wall outlets in modern society. She is intensely loved by her classmate Riko Saikawa.

Full Name: Ilulu. True Identity: An extremist dragon of the Chaos Faction from the same generation as Tohru. Role: Living at Kobayashi's house. Part-time clerk at the candy store "Oboro Shoten." Appearance: Short pink hair, petite but with extremely large breasts (flame-storing sacs). Personality: Initially attacked Kobayashi and the others out of hatred for humans, but after reconciling, she regained her original honest and spoiled nature. She loves children and looks up to Kobayashi as an older sister or mother figure. Abilities/Position: Possesses high combat ability and fire manipulation. She is a coworker at the candy store with Takeo Aida, a human of the same age, and has begun to develop feelings resembling love, showing a girl-like shyness and clumsiness around him.

Full Name: Quetzalcoatl (Lucoa in the human world). True Identity: A former goddess dragon of the Bystander Faction who once held divine status. Role: Responding to the summons of Shouta Magatsuchi, a boy from a mage lineage, she now lives at his house. Appearance: Heterochromia (right green, left gold), wavy blonde hair, and an outsized chest with revealing casual clothes. Personality: A laid-back, kind older sister figure. She dislikes conflict and watches over everyone with adult tolerance from a detached perspective. However, she has no sense of personal space and unconsciously seduces Shouta, who fears her as a "demon." Abilities/Position: One of the strongest beings in the series, possessing divine powers (such as rewriting the laws of the world). To Kobayashi, she is a precious "adult confidante" with whom she can discuss the balance of the world and dragon ecology.

Full Name: Fafnir (Takeshi Oyama in the human world). True Identity: A cursed jet-black ancient dragon of the Chaos Faction. Role: Living at the home of Makoto Takiya, Kobayashi's colleague. Appearance: Long black hair, round glasses, and butler-style clothing. His dragon form is a massive creature with many eyes and wings. Personality: Originally looked down on humans as "dust" with strong loathing, but became obsessed with online games due to Takiya's influence. He is now a hardcore gamer who truly loves human gaming and otaku culture. Generally blunt and caustic. Abilities/Position: Commands powerful curses and dark magic. He has built a deep bond of trust with Takiya as the "ultimate roommate to share hobbies with" (occasionally selling his own self-published manga at Comiket) and acknowledges Kobayashi's capabilities.

Full Name: Makoto Takiya. Occupation: Systems engineer at a system development company. Kobayashi's colleague and like-minded friend. Roommate: Fafnir (online gaming buddy and houseguest). Appearance: Usually a refreshing young man with brown hair. Wears swirl-pattern glasses when in otaku mode. Personality: Cheerful and competent at work. In private, he is a hardcore closet otaku (loves maids and games). Abilities/Position: A man with terrifying communication skills who managed to completely tame the vicious curse dragon Fafnir through online gaming. Tohru unilaterally views him as a "love rival" because of his close friendship with Kobayashi.

Full Name: Riko Saikawa. Occupation: 3rd-grade student at Oborozuka Elementary. Kanna's classmate and a leader in the class. Appearance: Twin-tails with an exposed forehead. A beautiful girl with an ojou-sama vibe, characterized by large green ribbons. Personality: Appears haughty but is actually a lonely, honest, and good child. Since falling in love with Kanna at first sight, she has been in a state of total devotion and blind adoration. When Kanna approaches her cutely or touches her, she falls into a trance, letting out a melted shriek of "Boheee~!" from the sheer bliss. Abilities/Position: An ordinary human, but Kanna's best friend.

Full Name: Shouta Magatsuchi. Occupation: 5th-grade student at Oborozuka Elementary. Heir to a mage lineage. Appearance: Short purple hair. Personality: Serious and hardworking, but at an age where he wants to act more grown-up. While he misunderstands Lucoa as a demon, he is conscious of her as a man and is constantly flustered and teased by her. Abilities/Position: His father is the Executive Director of Kobayashi's company (and actually a great mage). In Season 2, he struggles to make magic-infused charms to earn Lucoa's recognition. He respects Kobayashi as a "master mage" who commands dragons despite having no magical talent.