It is the period of the Warring States. In the country of Zipang, where gimmick robots and people coexist, there were rivalries between warlords that escalated into battles lasting all day and night. The gimmick robots also had a sharp aim for victory and glory. The gimmick robots are super humanoid robots (mechanical bio-creatures). One of the gimmick robots, Musashi from the Minamoto Village of Okayamana in the Chugoku Mountains, a pure, earnest leader of a gang, aims to become the top martial arts master, and goes on a journey of study. Musashi encounters his fateful rival, Kojiro, various gimmick robot swordsmen, heroes, and bad people, as he grows stronger while he fights.