Fullbody is a Marine officer who first appears in the East Blue as a self-assured and somewhat arrogant lieutenant. His name is derived from a term used to describe the quality of wine, reflecting an initial portrayal as a man who enjoys the finer things in life, particularly fine dining and romance. Physically, he is recognized by his well-combed pink hair, a scar beneath one eye, and a set of metal bolts attached to his knuckles, which serve as his primary weapons in combat.

At the outset of his introduction, Fullbody embodies a certain level of Marine authority and success. He is shown to be a capable fighter, easily dispatching the bounty hunters Johnny and Yosaku, and he carries himself with an air of superiority. This facade of competence is shattered during a date at the floating restaurant Baratie. When the chef Sanji exposes his lack of wine knowledge and later embarrasses him in front of his companion, Fullbody attempts to sabotage the restaurant by planting a fly in his soup. This petty act leads to a physical confrontation in which he is overwhelmingly and humiliatingly defeated by Sanji, an event that leaves a lasting grudge.

Following this defeat, Fullbody's character undergoes a significant and unexpected transformation, largely detailed in the cover page serial Jango's Dance Paradise. While off-duty on Mirrorball Island, he enters a dance contest and forms a deep friendship with the winner, who is secretly Jango, a former pirate and the hypnotist first mate of the Black Cat crew. Their bond is solidified when they join forces to defeat the Tulip Pirates. Fullbody demonstrates a strong moral code during this fight, refusing to attack the pirate captain who has taken an innocent woman hostage, even while suffering a brutal beating to protect her.

This event forces Fullbody to confront his duty. He arrests his new friend Jango, leading to a death sentence for the pirate. In a dramatic turn, Fullbody chooses friendship over his career, performing an impassioned protest dance in the courtroom that results in Jango's acquittal. The cost of this act is Fullbody's demotion from lieutenant to the lowly rank of seaman recruit. Just as the two friends are about to part ways, they both become instantly enamored with the beauty and strength of Captain Hina. They subsequently enlist as her subordinates, beginning a new chapter in their careers.

As a member of Hina's crew, Fullbody adopts a new nickname, Double Ironfist Fullbody, and begins to wear a more casual uniform, though he retains his signature knuckle bolts. His personality settles into a blend of his former arrogance and his newly discovered loyalty. He remains eager to capture the Straw Hat Pirates, particularly Sanji, to avenge his past humiliation, though these attempts are consistently foiled. He is almost inseparable from Jango, and the two are often seen acting in sync, dancing, and professing their admiration for Hina, who tolerates their antics while finding them bothersome. By the time of the series' timeskip, Fullbody has managed to regain his status as a commissioned officer, achieving the rank of major or lieutenant commander, which is actually one rank higher than where he began.

In combat, Fullbody is a skilled brawler who relies on a boxing-like style augmented by the metal bolts on his hands. He is a capable fighter by normal human standards, able to defeat ordinary pirates and bounty hunters with ease, though he is consistently outclassed by the superhuman fighters of the Grand Line. Beyond his fighting ability, Fullbody is also an exceptionally talented dancer, a skill that not only led to his friendship with Jango but also proved powerful enough to sway a military court. Throughout his journey from a pompous lieutenant to a demoted seaman recruit and finally to a loyal major, Fullbody is defined by his deep, if often comedic, loyalty to his friends and his adherence to a moral justice that prioritizes the protection of innocent civilians over absolute obedience to the law.