Goemon Ishikawa XIII, the thirteenth-generation descendant of the historical renegade samurai Ishikawa Goemon, joins the adventures of Arsène Lupin III. Initially an enemy tasked with killing Lupin or guarding secrets like sword-making formulas or alchemic knowledge, repeated failures and confrontations lead him to become Lupin's ally. He comes to value Lupin as both teacher and companion across manga, television series, and original video animations. His loyalty evolves from professional respect into genuine camaraderie, though he consistently criticizes Lupin's frivolous antics. He maintains a stoic, reserved demeanor, prioritizing meditation, martial discipline, and adherence to traditional Japanese customs. His attire consistently reflects this, consisting of a kimono, hakama, and zori, with color variations across series. He wields the sword Zantetsuken (Ryusei in manga), capable of cutting nearly any material, often declaring upon sparing lives: "I have cut yet another worthless object." His combat skills extend beyond swordsmanship to jujutsu and aikido, though he prefers non-lethal disarming. Key traits include extreme pride in his abilities, leading to intense shame upon failure or succumbing to weaknesses. These weaknesses encompass naiveté towards women perceived as innocent or trustworthy, frequently resulting in betrayal or manipulation, and susceptibility to scams promising enlightenment. He is easily bribed with Japanese cuisine and shows compassion for children, often prioritizing their protection. His discomfort with technology appears inconsistently, ranging from inability to operate basic devices to rare adaptability. In "Missed by a Dollar," he joins Lupin's plot to steal a ring linked to a legendary brooch. His subplot involves falling for a female cult leader, donating stolen money to her group, and being abandoned when she absconds with the funds, illustrating his recurring vulnerability to financial deceit and romantic exploitation. His broader relationships include mutual respect with Daisuke Jigen, whom he views as a fellow warrior, and distrust toward Fujiko Mine due to her manipulative tendencies, though he assists her when necessary. His ancestral connection to Ishikawa Goemon I is occasionally explored, notably in narratives involving artifacts like ukiyo-e prints or the Rosenkreuz pot, emphasizing his reverence for lineage. Across all media, he remains defined by unwavering principles, loyalty to Lupin's just causes, and a commitment to Bushido ethics, balancing his role as a thief with a moral compass.