The tale starts in the Tokugawa shogunate when Yui Shōsetsu meets the old Mori Sōiken, who, in the story, had survived to the Shimabara rebellion and learned the dark arts of ninpou in order to get his revenge.
Knowing they both wish for the dethroning of the shōgun, Soiken forms an alliance with Shosetsu and reveals a spell devised by him, the Makai Tensho, which can rise dead people as his puppets.
They soon gather an undead army of legendary warriors and sorcerers, among them Amakusa Shirō Tokisada, Miyamoto Musashi, and Araki Mataemon, and plan to use their supernatural skills to destroy the shogunate.
However, the crown of their army, Yagyū Jūbei Mitsuyoshi, breaks free from their control and becomes determined by his own reasons to stop their rebellion before it starts.
The roster of the dead varies depending on adaptation, but usually contains Amakusa, Musashi, Yagyu Munenori, and Hōzōin Inshun.