Musashi is a gimmick robot, a superhuman robotic warrior from Zipangu, a land embroiled in civil conflict reminiscent of the Sengoku era. In this setting, every person possesses their own gimmick robot, and these machines fight alongside humans in the region's power struggles. Identifying as a samurai-class gimmick robot, Musashi embarks on a journey determined to become the land's greatest samurai warrior.

His quest involves constant travel and numerous battles against both heroes and villains. His most significant conflict is his fierce rivalry with Kojiro, another master swordsman gimmick robot. This rivalry mirrors the historical feud between Miyamoto Musashi and Sasaki Kojiro, positioning them as lifelong adversaries who clash repeatedly throughout their journeys.

A pivotal shift occurs when their general assigns Musashi and Kojiro to escort Senhime, the general's granddaughter. This duty forces the rivals into an uneasy partnership. The princess's demanding and spoiled nature turns their mission into a series of misadventures filled with quarrels and complications, shifting their focus from individual combat goals to shared protective responsibilities.

During this escort mission, Musashi and Kojiro become entangled in a conspiracy to overthrow the general and seize control of Zipangu. This involvement thrusts them into larger political conflicts beyond their personal duel-focused objectives, placing them at the center of battles that will decide the country's rulership.

Musashi functions primarily within the context of his quest for supremacy, his rivalry with Kojiro, and his involvement in the political conflict surrounding Senhime's escort and the usurpation plot.