In the ultimate war of man vs. machine, the fate of humanity lies with a teenage cyborg named Shio! Living in constant fear of attack from machines, mankind depends on the cyborg corps known as the Guardians to keep them from harm as they await the arrival of the Kami, a godlike savior with mythical red blood who can grant only one wish to one person. Now, Shio, son of a Guardian, thinks he’s found the Kami–and all the Guardians are at war to get that wish!

Shio is forced by the tragedy of the machine war to team up with a mysterious girl from another world whose blood is the color red, just like the prophecies proclaim. Is this girl the human race’s last hope for survival in a world overrun by metal?