In Japan, humanity has achieved a golden age of prosperity powered by Blue Azure, a glowing, high-density energy source. It powers everything from floating transit trains to the smartphones in students' pockets. Humanity is highly advanced—think sleek holograms, mechanized armor, and energy-shielded cities—but still grounded enough that people live normal lives, go to convenience stores, and complain about homework. ​But Blue Azure has a dark side. Exposure to corrupted Azure turns technology and humans into horrific, bio-mechanical monsters known as Sentinels. To fight back, specialized academies train teenagers to become Aegis Agents, the thin blue line between civilization and extinction.