In the Japanese version, he was voiced by the late Makio Inoue and currently Daisuke Namikawa.
While Goemon might be considered one of Lupin's friends, it starts off more of a professional relationship than friendship. By the Red Jacket Series, Goemon has developed a true loyalty to Lupin, refusing to give away Lupin's secrets when tortured in one second series episode, for example. However, he easily gets annoyed by Lupin's antics, especially Lupin's infatuation with women and Fujiko in particular. He will occasionally oppose Lupin directly when Lupin's jobs or actions do not agree with Goemon's morals. He has even promised that the last act he will take with Lupin is delivering his deathblow. However, Goemon doesn't hesitate to help Lupin in serious situations, and readily assists him any time Lupin works for a just cause. Many theorize that Goemon associates with Lupin out of admiration for his profession, as Goemon's ancestor was a master thief himself.
Goemon has a much more amicable relationship with Jigen. Goemon sees Jigen as a fellow honorable warrior, while Jigen sees Goemon as a trustworthy "foxhole buddy," and the two are frequently paired together during jobs, and usually help keep Lupin in check.
On the odd occasion and increasingly in recent years, Goemon will ally himself with Fujiko, in spite of his distrust of her. As long as their goal is the same and Fujiko makes no attempts to betray him, the two work well together and usually achieve what they seek.
In the manga, Goemon first appears as a very dangerous enemy of Lupin. Lupin attempts to steal Goemon's master's alchemic formula through infiltration of Goemon's clan, but his cover is blown by Fujiko, who happens to be Goemon's girlfriend at the time. Goemon makes many attempts to kill Lupin over the next several volumes, making attempts ranging from hiring assassins as skilled as Jigen himself to entering the service of three martial masters to planting bombs in Lupin's belongings. Eventually, however, he is convinced that he could learn much more working for Lupin than against him, and rather abruptly switches his allegiance. His position at Lupin's side is cemented when Lupin ruins the government's case against the man who killed Goemon's uncle, allowing Goemon to take his revenge as brutally and publicly as he wants without having to break in to prison to do so.
By the events of the second manga series, Lupin trusts Goemon implicitly, and Goemon reciprocates. When a rival of Lupin captures and hideously tortures Goemon, Goemon refuses to even respond to his interrogation except to say that Lupin would find him and allow him to take revenge. Lupin then captures and seduces his rival's wife, and uses the information gleaned thereof to release Goemon, who slays his captor with Jigen's help.
Goemon has two members of his clan appear, but both use their talents to "satisfy their greed" as he once said, Kikyo and Sadachiyo the Scorpion.
In Dragon of Doom, Kikyo was once a childhood friend of Goemon. When she returned to aid Goemon, she was all grown up. She eventually became his love interest in the movie and traveled with him to get the small dragon figurine, which Lupin found from what's left of the Titanic. Later, Kikyo faked her death so she could turn on Goemon, steal the dragon figurine and side with Chin Chin Chao. Kikyo helped Chao to uncover the secret of the dragon figurine, and used its alloy to make an unstoppable stealth fighter. However, Goemon used his sword and skills to slice the fighter three times at the same spot. It was destroyed and Kikyo fell into the very same spot the Titanic sunk, resting with her grandfather, who stole the dragon figurine in the first place.
Sadachiyo the Scorpion appears in The Secret of the Twilight Gemini. He was a highly-trained assassin who was hired by a rogue faction within the Geltic tribe. Causing problems for both Lupin and Goemon throughout the special, Sadachiyo dueled Goemon to the death in the end. Sadachiyo's sword broke the tip of Goemon's Zantetsuken, only for the tip to land in Sadachiyo's back and pierce his heart.
In The Fuma Conspiracy, Goemon nearly marries into the Suminawa clan by marrying Murasaki Suminawa, the daughter of one of his instructors. The engagement eventually falls through because Goemon feels he is unworthy of being her husband, though he and Murasaki part on friendly terms.
Goemon Ishikawa XIII is a lifelong adherent of a number of Japanese martial arts, particularly Kenjutsu, Karate, Jujutsu and Iaidō. His training gives him many extraordinary talents (i.e. underwater breath control for diving without an aqualung, and a limited understanding of the supernatural). He can easily best several trained thugs in unarmed combat and catch an arrow or thrown dagger with his bare hands. His trademark skill is near-superhuman fleetness, enabling him to slice bullets in half before they make contact. It should be mentioned that, despite the deadliness of his weapon, Goemon will never take a human life unless challenged to a duel, and even then only if the opponent reveals a dishonorable nature. Although his Zantetsu sword gives him a virtually undefeatable advantage, it is Goemon's talent with the weapon that proves more valuable in a pitched battle. Goemon, like all the Lupin Gang, is also talented at disguises and impersonation, speaks several languages, and is a trained driver and pilot, although he prefers being a passenger rather than taking the driver seat.