Madarao is a demon wolf, more specifically a Honshū wolf, who has served the Sumimura family for approximately five hundred years. His name translates to "spotted tail," a reference to his white fur with grey spots. Prior to his life as a bound ayakashi, he was a wild dog known as Ginro. In that earlier era, he was acquainted with a character named Koya, though the exact nature of their relationship is rooted in the distant past.

In terms of personality, Madarao is often described as having a laid-back and moody temperament. He can appear indifferent and lazy, particularly when it comes to working with his current master, Yoshimori Sumimura. However, this surface demeanor belies a fierce sense of pride and loyalty. He is determined to prove that his skills in tracking and hunting ayakashi are superior to those of his rival, Hakubi, the demon wolf of the Yukimura family. When the situation demands it, Madarao rises to the challenge and shows a more focused and ruthless side, especially in combat.

Madarao's primary motivation is his duty to the Sumimura lineage and his own sense of rivalry with Hakubi. He takes his role as a guardian and tracker seriously, even if he grumbles about it. He also seems to have a personal stake in proving his experience and worth, as he is significantly older than Hakubi and does not wish to be outdone by a younger wolf. His loyalty to the Sumimura family is deep-seated, stemming from a long history of service.

His role in the story is that of a companion and support for Yoshimori Sumimura. He serves as the Sumimura family's demon dog, using his acute sense of smell to detect ayakashi, which is a crucial ability for the kekkaishi. He often accompanies Yoshimori on night patrols and provides both combat assistance and occasional guidance. Madarao acts as a link to the family's past, having served multiple generations. He also serves as a counterpoint to Hakubi, creating a dynamic of friendly competition between the two wolves that mirrors the rivalry between their respective human partners.

Key relationships include his bond with Yoshimori Sumimura, whom he serves as a partner despite his occasional irritation with the young kekkaishi. He shares a long-standing rivalry with Hakubi, the Yukimura family's wolf, which is characterized by bickering but also mutual respect in battle. His past connection with Koya is a notable part of his history, as is his service to the Sumimura family founder, Tokimori Hazama, for whom he held deep affection. He also has a relationship with Shigemori Sumimura, Yoshimori's grandfather, given his long tenure with the family.

In terms of development, Madarao remains a consistent figure throughout the series. While his personality does not undergo drastic change, his interactions with Yoshimori deepen over time. He learns to trust Yoshimori's judgment even when he doubts it, and he gradually becomes more willing to put himself at risk for his young master's sake. His past with Koya and his true nature as a powerful ayakashi become more relevant as the story progresses, revealing layers of history that affect his present actions.

Madarao's notable abilities center on his sensory and combat skills. He possesses an extraordinarily keen sense of smell, allowing him to detect ayakashi from great distances and track them even when they hide their presence. This makes him an invaluable asset to the kekkaishi. He wears a collar made of spirit beads that seals away his true demon form. When the seal is removed, he reverts to his full wolf form and gains access to potent abilities. In that state, he is a skilled poison user, able to deliver lethal venom through his fangs or tail. He is also an adept illusionist, capable of creating deceptive images to confuse or misdirect enemies. In his sealed form, he appears as a smaller dog-like creature, but his combat effectiveness remains considerable due to his experience and instincts.