Arriving on Earth via meteor impact amid the dinosaur crisis, the extraterrestrial Musashi belongs to an unidentified species. His mission focuses on countering Grottes and the dinosaur army, leveraging advanced knowledge of their tactics and weaknesses—particularly Grottes' regenerative medallion.

Musashi maintains a humanoid appearance through a surface-level human disguise, though his true physiological traits remain undetailed. He operates alongside Golda, a golden dinosaur kaiju summoned through his cross-shaped device. This device also facilitates communication, establishing their symbiotic partnership where Musashi directs Golda in combat.

His involvement begins with strategic warnings to D-Force about Grottes and Zobina's impending disasters. He intervenes critically in battles, deploying Golda to free Aizenborg from Shizala’s ice trap—enabling Zobina’s defeat. During the final confrontation, Musashi identifies Grottes’ medallion as the source of immortality and instructs Aizenborg to destroy it.

Musashi’s arc concludes in self-sacrifice during the assault on Grottes’ underground empire. While ensuring Aizenborg strikes the medallion, he suffers fatal retaliation from Grottes. D-Force recovers his body, conducts burial rites, and seals the dinosaur realm. Posthumously, liberated kaiju—including formerly hostile species—celebrate their freedom, cementing his legacy.

In expanded media, Musashi appears in the documentary *Return of Izenborg*, featuring new narrative sequences using enhanced original suits. The documentary examines the series’ cultural impact and incorporates behind-the-scenes perspectives.