Fu Orostor is a supporting character in the manga and anime series Gachiakuta. He is a young man of seventeen years with a short and slender build, standing at 160 centimeters tall. His most distinctive physical features include his two-toned hair, which is blonde at the top and darker at the tips, as well as his blue eyes that possess a unique ring around the pupil. He typically wears a coat stitched to a patchwork puffer jacket, baggy trousers, sandals, and a mask that covers his face.

Fu's personality is defined by his extreme timidity and cowardice. He is acutely anxious, lacks self-confidence, and is notably inexperienced in combat, to the point of not even knowing how to initiate a fight. This psychological fragility stems from a deep-seated fear of taking responsibility for his own actions. Fu rationalizes that if he follows orders from an authoritative figure, the blame for any consequences falls upon the one who gave the command, not upon himself as the tool who carried it out. Consequently, he feels unable to function or make decisions without direct orders, a trait that manifests in his desperate need for a strong leader to follow. His preferences reflect this dependency, as he likes an absolute ruler and dislikes self-determination.

Despite his nervous demeanor, Fu is a Giver, a person who can channel their emotions into objects to create powerful Vital Instruments. His Vital Instrument is a doll named Hii, which he carries with him. Hii possesses its own distinct, more aggressive personality and looks down on Fu's cowardly nature. The primary ability of this Vital Instrument is possession. When Fu allows it, Hii can take control of his body, leading to a dramatic transformation. While possessed by Hii, Fu becomes a highly capable and combative fighter, with his power, speed, and technique increasing significantly, turning him into a formidable opponent who is considered a valuable asset in battle. However, this power comes with a drawback; after the possession ends, Fu is often left confused and with no memory of his actions during the fight, indicating he does not have full control over his own ability.

In the story, Fu is initially a rookie member of the Raiders, a group of outlaws led by Zodyl. He is intensely loyal to Zodyl and follows his commands without question, living in fear of what would happen should he fail. During the Trash Storm Arc, Fu is tasked with fighting Enjin, a senior member of the opposing Cleaners. His timid nature causes him to fail this mission, and he is ultimately abandoned by Zodyl, who sees him as a disappointment.

Abandoned and left to die inside a giant trash beast, Fu is guided by his doll Hii to seek out a new master. He approaches the Cleaners and begs Enjin to let him become his minion. Initially distrustful of the former enemy, Enjin reluctantly agrees to let Fu join the Cleaners on a trial basis, setting the stage for his role as an uneasy ally. His key relationships are therefore defined by his need for masters: first with Zodyl, whom he feared, and then with Enjin, whom he respects for his authoritative and cool demeanor. He also develops a functional relationship with Amo Empool, as he does not mind taking orders from her even when she seems to dislike him.

Fu's character development centers on his transition from a discarded pawn to a probationary member of a new group. While his core personality remains anxious, his arc demonstrates a degree of tenacity and a survival instinct that drives him to find a new place for himself after being cast out. His journey explores themes of dependency, responsibility, and the search for personal identity in a harsh world.