The story opens in the Tokugawa shogunate shortly after the brutal suppression of the Shimabara Rebellion. The sorcerer Mori Sōiken, a survivor of the rebellion who has mastered forbidden ninpou arts, performs the dark ritual known as Makai Tenshō, which allows him to resurrect the dead by using a woman’s body as a vessel. He is discovered by the strategist Yui Shōsetsu and the swordsman Miyamoto Musashi while bringing the rebel leader Amakusa Shirō Tokisada and the duelist Araki Mataemon back to life. Shōsetsu immediately pledges himself to Sōiken’s cause.

Sōiken’s goal is to overthrow the shogunate, and over the following years he and Shōsetsu gather an undead army of legendary warriors and sorcerers. The resurrected figures retain their full combat skills but lose their moral restraints, becoming cruel and ruthless. The roster includes Miyamoto Musashi, the spear master Hōzōin Inshun, the avenger Tamiya Bōtarō, and eventually even Yagyū Munenori, the father of the famous swordsman Yagyū Jūbei Mitsuyoshi. The ultimate prize of Sōiken’s plan is Jūbei himself, whom he intends to resurrect and add to the army as its most powerful member.

Jūbei, however, breaks free from Sōiken’s control and becomes the primary obstacle to the conspiracy. After learning of the plot, he gathers a small band of trusted retainers—the ten men of Yagyū—and sets out to stop the resurrected warriors one by one. The conflict unfolds across the Kii Peninsula and the roads leading to Edo, with Jūbei engaging each member of the demonic army in a series of duels that test his skill, resolve, and humanity.

A major narrative arc involves the political machinations of Tokugawa Yorinobu, the lord of Kii domain, whom Sōiken secretly manipulates into rebelling against the shogunate. Yorinobu provides the resurrected army with a legitimate base of operations and even attempts to march on Edo. Jūbei must not only defeat the undead swordsmen but also outmaneuver the political conspiracy. Along the way, he encounters several kunoichi—female agents turned into vessels for the resurrection ritual—whose tragic fates underscore the horror of Sōiken’s magic.

The climax of the novel is a final confrontation between Jūbei and the last and most formidable of the resurrected, Miyamoto Musashi. The duel takes place on a small island off the coast of Kuwana, a deliberate echo of Musashi’s famous duel with Sasaki Kojirō. Jūbei anticipates that Musashi will fight with a wooden sword, and in a desperate reverse of the historical outcome, Jūbei splits both the wooden sword and Musashi’s body. With Musashi’s defeat, the conspiracy collapses. Yorinobu abandons his rebellion, Sōiken is killed, and Jūbei sails east, leaving the aftermath behind.

The setting is the early Edo period, with its rigid social hierarchy, simmering resentment from the fallen Christian rebels, and the powerful Tokugawa clan’s grip on power. The narrative moves from the desolate battlefield of Shimabara to the quiet villages of Yagyū territory, the imposing castle towns of Kii, and finally to the isolated island where the last battle occurs. The central conflict is between the living and the resurrected dead, but also between duty and personal loyalty, as Jūbei is forced to kill his own father, Yagyū Munenori, who became a demonic puppet.

Notable narrative arcs include the gradual corruption of each historical figure as they succumb to Sōiken’s temptation, the tactical cat-and-mouse game between Jūbei and the resurrected army, and the moral weight of defeating enemies who were once legends of the sword. The novel is structured as a series of escalating duels, each highlighting a different fighting style and personality, building toward the ultimate confrontation with Musashi.