The story begins in 1600 amid the bloody aftermath of the Battle of Sekigahara. Seventeen-year-old Shinmen Takezo and his friend Matahachi survive the slaughter but are separated when Matahachi abandons him. Takezo returns alone to his home of Miyamoto Village, where the locals treat him as a violent, demonic pariah.
Hunted like an animal by the authorities, Takezo flees into the mountains, unleashing a feral rage against anyone sent to capture him. His bloodlust is finally halted by Takuan Soho, an eccentric Buddhist monk. Instead of killing him, Takuan forces the young warrior to confront his inner demons and the value of human life.
To save him from his dark past, Takuan grants him a clean slate and renames him Musashi Miyamoto. Reborn and unbound, Musashi leaves his village behind to embark on a lifelong pilgrimage to become "unrivaled under heaven."