Kyon-Kyon is a character from the world of Demon China who appears as a secondary figure in the story. She is a jiangshi, a type of Chinese hopping vampire, but she is an unusual one, possessing both great power and a gentle heart. Her primary motivation stems from a tragic past: she was originally a human girl who lived with her twin sister, Ran-Ran, in a village. During a war, their village was attacked and both sisters lost their lives. They were transformed into jiangshi, initially losing their humanity and preying on the living. A powerful demon master, who took the form of a tiger, was summoned to stop them. Instead of destroying them, the master defeated them and took them under their tutelage, helping Kyon-Kyon and Ran-Ran regain their human hearts while retaining their supernatural abilities, making them high-ranking jiangshi.

Driven by the belief that performing good deeds in the human world will allow her to become human once more, Kyon-Kyon leaves Demon China to live among people. Her goal defines her daily life and interactions. To support this dream, she works at Dragon Books, a bookstore in the Jinbocho district, a job she obtained through the character Yurine Hanazono.

In terms of personality, Kyon-Kyon is fundamentally kind, caring, and eager to help anyone she perceives to be in trouble. She has an innocent and sincere demeanor, which is reflected in her unique speech pattern of ending her sentences with "yo". However, this gentle nature has a sharp and violent contrast. When confronted with people she considers truly evil, especially those who harm innocent people or insult her sister, she becomes brutally unforgiving and loses control. On several occasions, she has nearly beaten criminals to death, only being stopped by the intervention of her sister, Ran-Ran. She also has a literal-minded side and often fails to understand jokes, which can lead to confusion or disappointment for those around her.

Kyon-Kyon's most important relationship is with her twin sister, Ran-Ran, who has been transformed into a panda-like form. Despite occasional bickering, such as when Ran-Ran is annoyed by Kyon-Kyon sharing half-eaten food, their bond is incredibly strong. Ran-Ran is often the one who must physically restrain Kyon-Kyon when her violent side threatens to go too far. Kyon-Kyon also forms a friendly bond with the demon Jashin-chan, with the two of them affectionately referring to each other as dumb demons. She respects Yurine Hanazono for helping her find employment. Her interactions with others are frequently marked by her pure honesty, which can be surprisingly touching, and her habit of sharing her food, which others find a bit unsettling.

Despite her small stature of 148 centimeters, Kyon-Kyon possesses immense physical strength, allowing her to fight on equal terms with the powerful demon Minos. Unlike common jiangshi that move by hopping, she can move freely and act on her own will. Her body, however, has a notable weakness: it is fragile. A strong impact can cause her to break apart like a mannequin, though she can be quickly reassembled with help. Furthermore, like many jiangshi, she remains dangerously vulnerable to glutinous rice, a weakness her master neglected to teach her to overcome. Throughout her time in the human world, Kyon-Kyon struggles to balance her kind dream of becoming human again with the wild, violent impulses that arise from her protective and vengeful nature, often relying on her sister to help her maintain that balance.