"The Empire of Corpses" is a manga adaptation of a novel by Project Itoh, set in an alternate 19th-century world where reanimating the dead has become a scientific reality. The story unfolds in a steampunk-inspired universe where reanimated corpses, known as "the Dead," are used as laborers and soldiers, fundamentally altering the course of history. The narrative centers on John Watson, a young medical student in London who is secretly conducting illegal experiments to restore full consciousness to the Dead. His motivation stems from the loss of his close friend, Friday, whose corpse he reanimates but fails to fully restore to its former self.

Watson’s illicit activities attract the attention of the British government, and he is coerced into joining a covert mission to retrieve the notes of Victor Frankenstein, the legendary scientist whose work laid the foundation for modern corpse reanimation. The government believes Frankenstein’s research holds the key to creating a fully conscious Dead, a breakthrough that could shift the balance of power in a world teetering on the brink of war. Watson is paired with a reanimated corpse named Frederick Burnaby, a former soldier, and together they embark on a globe-trotting journey that takes them from London to Afghanistan, the United States, and Japan.

As the mission progresses, Watson encounters a diverse cast of characters, including Hadaly Lilith, a mysterious and highly advanced Dead who exhibits signs of true consciousness. Her existence challenges the ethical and philosophical boundaries of reanimation, raising questions about the nature of life, death, and humanity. The narrative delves into the moral dilemmas surrounding the use of the Dead, exploring themes of exploitation, identity, and the consequences of playing god.

The story is driven by political intrigue, as various nations vie for control over Frankenstein’s research, each seeking to weaponize the Dead for their own gain. Watson’s journey becomes increasingly perilous as he uncovers the darker implications of the technology he seeks to master. The manga weaves together elements of historical fiction, science fiction, and horror, creating a richly layered narrative that examines the intersection of science, morality, and power in a world where the line between life and death has been blurred.