Fue is a mysterious adult male character who appears at the beginning of the story and serves as the primary catalyst for the main character's journey. He has gray eyes and gray hair that reaches his shoulders, and his appearance is often completed by a hat and a coat. His role is that of a guide who invites the protagonist Sanshiro to participate in a supernatural game. Fue arrives without warning, speaks of adventure, and instructs Sanshiro to peel a seal that appears, which provides the starter kit for the game known as Bakegyamon. He then transports Sanshiro to a parallel world called Backwards Japan, a reverse version of the country, where the game takes place.

Fue is also identified as Sanshiro's koma, which is a term for a partner or assigned creature within the context of the game. This makes him a direct companion to the main character throughout the competition. His motivations are tied to the game itself, which occurs every forty-four years and brings together many children to compete for a single granted wish. The game involves demons, known as Ayakashi, that have been sealed into cards called Gekifu for the players to use in battles. Fue facilitates Sanshiro's entry into this world, and his relationship with the protagonist is central to the story's progression. While other players often treat their assigned creatures as mere tools or items, Sanshiro develops a sympathetic and respectful bond with his partner, and Fue is specifically mentioned as being part of this dynamic, with Sanshiro's compassionate nature extending to him. The overall narrative focuses on the various players and their reasons for joining the tournament, with the main character's wish being to free all the demons if he wins, a selfless goal that contrasts with the desires of many other participants. Information on Fue's personal background, internal motivations, significant character development throughout the series, or detailed combat abilities is not available in the provided search results.