Goemon Ishikawa XIII is a master swordsman and a recurring partner to the gentleman thief Arsène Lupin III. As the thirteenth generation descendant of the historical outlaw Ishikawa Goemon, he carries on a family legacy that blends thievery with a strict code of personal honor. Outwardly, Goemon is defined by a stoic and reserved demeanor, often spending his downtime in deep meditation, detached from the more rambunctious antics of his companions. Despite his calm exterior, he possesses an intense sense of pride in his abilities, particularly his swordsmanship, and will withdraw to train or meditate if he feels he has shamed himself or his craft. He is a traditionalist in almost every sense, preferring Japanese clothing, cuisine, and customs even while participating in international capers. This loyalty to his heritage is balanced by a notable weakness for both traditional Japanese food and trustworthy-seeming women, often leading him into troublesome situations.

His primary motivation is the pursuit of honor and the perfection of his skills with his legendary sword, the Zantetsuken, which is said to be capable of cutting through almost any substance. While he typically refrains from lethal force, preferring to disarm or disable opponents by cutting their weapons or clothing, he will engage in serious combat when his code or his allies demand it. In the 2003 television special Operation Return the Treasure, Goemon plays a vital role in the team's unique mission. The story sees Lupin and his crew hired to return a collection of stolen artifacts to their original locations rather than stealing them for themselves. Within this context, Goemon is depicted as wounded yet still fighting fiercely to protect his honor, demonstrating his unwavering commitment even when physically compromised. His incredible reflexes and mastery of the sword prove invaluable for overcoming the physical obstacles and armed adversaries that the team encounters during their recovery efforts.

Goemon’s primary relationship is with Lupin, which is complex and built on a foundation of mutual respect that evolved from a violent rivalry. While he has pledged that his final act with Lupin may be to deliver a deathblow, he is profoundly loyal and will not hesitate to help when the cause is just or when Lupin is in genuine peril. He is frequently annoyed by Lupin’s lecherous and hedonistic tendencies, which clash with his own disciplined lifestyle. In contrast, his relationship with Daisuke Jigen is far more amicable. He regards Jigen as a fellow warrior and a trustworthy partner, and the two are often paired together to handle the practical aspects of a heist. He holds Fujiko Mine in a state of constant distrust due to her duplicitous nature, though he may occasionally work alongside her if their immediate goals align.

Throughout the operation in Return the Treasure, Goemon’s personal development is tied directly to his honor and resilience. The fact that he continues to fight effectively while wounded illustrates that his sense of duty and his personal code of ethics are powerful enough to overcome physical limitations. His abilities remain nothing short of extraordinary. He is a master of multiple martial arts, including kenjutsu, iaido, and jujutsu, allowing him to defeat groups of armed thugs without drawing his sword, or to perform feats such as slicing bullets in half in mid-air. His trademark ability is the speed and precision of his draw, which he often uses to cut inanimate objects, lamenting his actions afterward with the phrase, "I have cut yet another worthless object". In Operation Return the Treasure, these skills are placed in service of a plot that frequently upends the gang's usual dynamic, but Goemon remains a steadfast, honorable, and nearly unstoppable force for the team.