Gin, also known as Gin the Demon Man, serves as the combat commander and loyal right-hand man of the Don Krieg Pirates, playing a significant role during the Baratie arc. His background is largely tied to his captain's ill-fated voyage to the Grand Line. He was present when the Krieg armada was nearly annihilated by the Warlord of the Sea, Dracule Mihawk, an event that left a deep psychological scar on Gin as he witnessed the destruction of his comrades and their fleet. Following this disaster, Gin demonstrated early on his willingness to sacrifice for his captain by disguising himself as Don Krieg to draw away marine pursuers, an act that led to his capture and imprisonment aboard a marine ship.

Gin is defined by a profound internal conflict. On one hand, he is the Demon Man, a warrior known for his absolute loyalty to Don Krieg, carrying out any order with brutal, ruthless efficiency without protest. This loyalty is rooted in a mixture of deep respect and palpable fear of his captain's power, compelling him to obey even commands that lead to his own demise. On the other hand, Gin possesses a strong, hidden sense of honor and gratitude that stands in stark contrast to his captain's unscrupulous nature. He is unable to reconcile his role as a ruthless killer with the simple act of kindness he receives, which becomes the central motivation for his actions. After being starved and weakened for days, he is given a free meal by Sanji, the chef of the Baratie, and this single act of compassion creates an unbreakable debt of honor that prevents Gin from carrying out his orders to harm the restaurant.

This conflict drives Gin's role in the story. Initially, he advises Monkey D. Luffy against sailing to the Grand Line, speaking from his own terrifying experience. When the remnants of the Krieg Pirates invade the Baratie, Gin is horrified by his captain's lack of gratitude toward their benefactors but is forced to obey. His pivotal moment arrives when he is ordered to kill Sanji and, despite having the advantage in their fight, he absolutely refuses, even going so far as to beg Krieg to spare the chefs. In retribution for this disobedience, Krieg disowns Gin and releases a deadly poison gas, the MH5. Though Gin has a gas mask, he throws it to Luffy, who had none, thereby sacrificing himself and inhaling the lethal poison. This act of selflessness turns the tide of the battle, fueling Luffy's fury to defeat Krieg.

Gin's key relationships are the primary drivers of his character arc. His relationship with Don Krieg is one of toxic subordination based on fear and admiration for power, but Krieg's cruelty ultimately severs this bond, leading Gin to personally knock Krieg unconscious after Luffy's victory, declaring that they must admit defeat and start over. His relationship with Sanji is the most transformative; as the first person to show him genuine kindness, Sanji becomes a symbol of the morality Gin thought he had lost. This is mirrored by his growing respect for Luffy, who demonstrates a different kind of strength by defeating Krieg and telling Gin not to follow such a cruel man, a sentiment Gin echoes as he departs.

Despite being a subordinate, Gin is a highly capable and formidable fighter. The Baratie cooks initially mistake his weakness for hunger, but he quickly proves them wrong, showcasing his resilience by escaping the marine ship and defeating multiple guards even after days of starvation. His combat style is aggressive and direct. He primarily wields a pair of tonfas tipped with heavy iron balls, a weapon he uses with great speed and precision. Notably, he uses these tonfas to destroy Pearl's supposedly indestructible iron shields with a single blow, something Sanji had been unable to accomplish. He is also shown to be proficient with firearms, using a flintlock pistol and a shotgun. His strength is such that a weakened Gin could match a skilled martial artist like Sanji in combat. Following the Baratie incident, Gin takes the defeated Krieg and his remaining crew and sails away on a small boat given to them by the restaurant. Before leaving, he expresses his hope to meet Luffy again on the Grand Line. Reports later indicate that he survived the poison and was seen with Don Krieg in the world's underworld.