Goemon Ishikawa XIII is a fictional character created by Monkey Punch for his manga series Lupin III, which debuted in Weekly Manga Action on August 10, 1967. Goemon is the thirteenth generation of renegade samurai, a descendant of the historical figure Ishikawa Goemon. He is usually quiet and participates in Arsène Lupin III's exploits less frequently than Daisuke Jigen. In the original manga, Goemon first appears as a very dangerous enemy of Lupin in chapter 28.
Lupin attempts to steal Goemon's master's alchemic formula through infiltration of Goemon's clan, but his cover is blown by Fujiko Mine, who is Goemon's girlfriend at the time. Goemon makes many attempts to kill Lupin over the next several installments, making attempts ranging from hiring assassins as skilled as Daisuke Jigen himself, to entering the service of three martial arts masters, to planting bombs in Lupin's belongings. However, he later decides that he could learn 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 into prison to do so. By the events of the second manga series, Lupin trusts Goemon implicitly, and Goemon reciprocates. When a rival of Lupin's 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. In the original anime Goemon's relationship to Lupin starts off more professional than close friendship. By the second anime series, Goemon has developed a true loyalty to Lupin. However, he easily gets annoyed by Lupin's antics, especially Lupin's infatuation with women, Fujiko Mine in particular. He will occasionally oppose Lupin directly when Lupin's jobs or actions do not agree with his 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. However, in 1978's The Mystery of Mamo (originally titled simply Lupin III), he claims that he helps Lupin simply so he can keep his vow to kill him 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.