Goemon Ishikawa XIII serves as a samurai associate within Lupin III's group. In this narrative, he encounters Isabelle during an Alaskan snowstorm, rescuing her from attackers linked to the secret society Conquer the Universe, Inc. (also known as the Three Masons). He becomes her bodyguard as she pursues the Super Egg diamond, developing romantic feelings for her. This attachment reflects his established tendency to form protective bonds with women he perceives as vulnerable, showcasing his loyalty and emotional depth.

His martial skill remains central, wielding the Zantetsuken sword capable of cutting nearly any material. He demonstrates this by severing a helicopter during a confrontation. Later, witnessing Isabelle's betrayal and mortal injury, he destroys the Super Egg diamond itself with the Zantetsuken, combining precision with profound emotional response.

Goemon consistently adheres to traditional Japanese practices, maintaining characteristic composure and deep meditation even in perilous situations. His cultural preferences shape his demeanor and combat style. While typically reserved, his reactions to Isabelle's plight—displaying visible frustration and decisive action—reveal moments where strong emotion overrides his usual stoicism. Following these events, he departs for Alaska, continuing his pattern of seeking solitude after significant experiences.