Gido is a fighter encountered on the 200th floor of the Heaven's Arena, where he serves as an early obstacle for the protagonist Gon Freecss. His background is directly tied to his introduction to Nen, the series' life energy manipulation system. Gido managed to reach the 200th floor without any knowledge of Nen, a testament to his basic combat skills. However, upon reaching this level, he was subjected to a malicious aura attack by an opponent, a cruel form of baptism that forcibly awakened his Nen but cost him both of his legs, which were replaced with a metal peg leg that he uses alongside a wooden cane for support. In a notable difference, the first anime adaptation portrayed his peg leg as a prosthetic used only for combat, suggesting he still has both of his natural legs.

Gido possesses a ruthless and pragmatic personality. He is willing to resort to underhanded tactics like kidnapping and blackmail to manipulate his opponents and secure victories. He is also somewhat sadistic, taking pleasure in the helplessness of inexperienced fighters. This behavior stems from his primary motivation: to become a Floor Master of Heaven's Arena. He seeks the money and fame that accompany the title but is acutely aware that he lacks the necessary strength to earn it fairly. Consequently, he deliberately targets and preys upon newcomers who have not yet mastered Nen, stacking the odds in his favor.

Gido plays a significant role in the Heaven's Arena arc as an antagonist who demonstrates the practical and dangerous applications of Nen in combat. He is part of a trio of fighters on the 200th floor that also includes Riehlvelt and Sadaso. Together, they collaborate to bully and scheme against newcomers, though their alliance is largely one of convenience and shared tactics rather than genuine friendship. Gido is the first to face Gon in a formal match. He easily defeats Gon, who has only just learned the most basic Nen techniques, breaking the young fighter's arm in the process. This defeat forces Gon to undergo rigorous training. In their rematch, a more skilled Gon overcomes Gido's strategy by using his fishing rod to lift the arena floor slab, toppling Gido and destroying his metal leg, thus securing a definitive victory. Following this loss, Gido is forced to forfeit his subsequent match against Killua by default, concluding his role as a direct threat. His primary narrative function is to highlight the immense speed of Gon's growth; he is a measuring stick that Gon surpasses after mastering the fundamentals of Nen.

Gido is an Enhancer, meaning his Nen type is best suited for amplifying the natural power of objects or his own physical abilities. His entire fighting style is built around the use of spinning tops, which he enhances with his aura to become deadly projectiles. He can infuse multiple tops simultaneously and, by combining Enhancement with Manipulation, give them simple commands like repelling anything in a given area. However, due to the poor compatibility of Enhancement and Manipulation types, he cannot issue complex orders, and his tops attack somewhat indiscriminately. His known techniques include Battle Waltz, where he releases a swarm of spinning tops to create a hazardous field, and Shotgun Blues, where he launches several tops directly at a target like a volley of bullets. His most notable ability is Tornado Top, a purely Enhancement-based technique where he uses his metal peg leg as an axis to spin his entire body at incredible speeds. This spinning motion serves as both an impenetrable defense and a powerful ramming attack. Gido has trained himself to withstand the violent dizziness such rapid spinning would normally cause. Despite the effectiveness of these abilities against novices, Gido himself admits to having no real strength, and his equipment has proven to be fragile, breaking upon contact with sufficiently powerful Nen users.