Wanyuudou, a youkai and principal companion to Ai Enma, originated as a tsukumogami born from the left wheel of a royal carriage destroyed over four centuries ago. When wartime attackers ignited the fleeing vehicle and sent it plummeting off a cliff, the detached wheel—still aflame—awoke as a sentient entity. It haunted nearby villages in its monstrous form: a fiery wheel with a human face embedded in its hubcap. Ai eventually subdued him, granting a human guise and binding him as her first ally. His human visage manifests as a composed, bald elder with narrow eyes, draped in seasonal variations of traditional attire: a dark red-brown haori and yukata transitioning to muted brown and gray, accented by a gray fedora and red scarf. He retains his blazing wheel form, levitating and igniting surroundings, and can morph into a full carriage to ferry Ai. His abilities extend to fire manipulation, conjuring memory illusions, possessing vehicles, and magically altering clothing for stealth. At Ai’s command, he shifts into a black straw doll bound by red string. Though mild-mannered and inclined toward diplomacy, Wanyuudou wields formidable strength—halting speeding trucks barehanded—and deep expertise in supernatural matters. His dry humor and unwavering loyalty to Ai contrast with a persistent animosity toward Kikuri, another entity linked to their circle. After Ai’s temporary demise, he assumes mortal roles as a construction laborer and school janitor, supporting her successor Yuzuki Mikage before reuniting with Ai upon her return. Details of his involvement in films, OVAs, or spin-offs beyond the central narrative remain unspecified.