In 2025, roboticist Yuuki Fudou runs a company buried in debt and refuses to let his robots be used for crime or war, but without a backer his firm is finished. Recommended by his old friend Asuka Ryou, he joins a project in an arms maker's underground lab studying the Demon Wall Painting, a prehistoric mural recovered from Antarctic ice, and the Demon Armor found with it. The armor turns out to have a will of its own, members of his research team are taken over by it, and robot suicide bombings begin to hit Japan, until Yuuki merges with the armor of Amon to fight back.