Kanna Kamui is a young dragon from another world who comes to live on Earth after being exiled from her home realm. Although her actual age spans hundreds of years, her appearance and behavior are analogous to a human child around eight or nine years old, and she attends elementary school. Her origins are rooted in mischief; she was sent away as punishment for pulling too many pranks, a behavior that stemmed from a desire to gain attention from her parents. At the start of her story, she arrives seeking out her fellow dragon Tohru, whom she initially believes was seduced away from their world by the human woman Kobayashi. Kanna is quickly welcomed into Kobayashi's home, where she finds the family structure she was lacking and begins to call herself Kanna Kobayashi.

Kanna presents a quiet and stoic exterior, often appearing with an expressionless face and speaking in a soft-spoken, minimalistic manner. However, this reserved demeanor masks a deeply emotional and at times mischievous personality. She is highly inquisitive about the human world, approaching everyday objects like cars and playgrounds with genuine curiosity. Despite her ancient lineage, she acts very much like a child, enjoying frequent naps, having a seemingly bottomless appetite for snacks, and occasionally using her cuteness to manipulate those around her to get what she wants. Her dragon nature surfaces in her habits of eating small animals and insects whole, as well as her immense strength and speed, which she must consciously temper when interacting with human friends.

Her primary motivation shifts from returning to her own world to finding a permanent place in her new one. Having been rejected by her biological parents, she seeks and gradually forms powerful attachments that fill that void. She views Kobayashi as a surrogate mother and Tohru as an older sister, and her deepest desire is to maintain the security and affection of this unconventional family unit. This motivation also drives her to integrate into human society, leading her to eagerly attend school and participate in activities like sports festivals and class plays simply because she wants to experience the normalcy and connection that human children enjoy.

In the narrative, Kanna serves as a central figure that binds the core group together. Her presence transforms the dynamic between Kobayashi and Tohru, creating a family unit that softens both of them and provides a constant source of slice-of-life scenarios. Her role often involves navigating the tension between maintaining her secret dragon identity and forming genuine human relationships. She becomes a bridge between the two worlds, and her vulnerability as a child who needs protection also makes her an emotional anchor for the story, highlighting themes of found family and belonging.

Kanna's relationships are central to her character development. Her bond with Kobayashi is the most significant, evolving from initial hostility to a deep, trusting filial love. At school, she develops a close, intense friendship with her classmate Riko Saikawa, who is fascinated by her. This relationship allows Kanna to experience peer friendship and normal childhood interactions, though it is often played for comedy as Riko's obsession grows. She also has a connection with her biological father, Kimun Kamui, who appears later in the series and shows a desire to be part of her life, creating a complex dynamic between her past and present families.

Throughout her time on Earth, Kanna undergoes notable development. She evolves from an initially lonely and slightly bitter exiled child into a more confident and expressive individual. While she remains largely stoic, she learns to show affection openly and experiences true happiness within her new family, culminating in rare moments where she genuinely smiles. She becomes more adept at understanding complicated human emotions and social cues, growing from a being who saw human customs as strange puzzles to a girl who fully embraces her identity as a member of Kobayashi's household.

Kanna possesses a wide array of magical abilities befitting a dragon of her heritage, with her specific domain being electricity and thunder, directly referencing the Ainu kamuy (god) she is named after. In her human form, she retains superhuman strength, speed, and durability, capable of fighting on par with other powerful dragons like Tohru. Her signature ability is the generation and manipulation of electricity, which she can discharge as powerful energy beams or use to enhance her physical attacks. A unique and famous trait is her method of recharging her magical energy; she inserts the fluffy bulb on the end of her tail into a standard electrical outlet. She is also capable of transforming into a large, feathered dragon, flight, dimensional travel, and has enhanced senses such as x-ray vision and extrasensory perception. While powerful, her abilities are somewhat limited compared to adult dragons; she cannot use advanced perception-blocking magic without it appearing flawed, and her power requires regular recharging to remain at peak levels.