Park Gwangseok is an average office worker who enjoys reading web novels as a hobby. And as he's reading one night, the author of his favorite story, "The Great Demon War," asks him to save the world. After a flash of light, he finds himself sitting on a throne in the body of Emperor Axeltrion, the villain of the novel. But the worst part is that Axeltrion's murderous instinct makes him crave bloodshed! Can Gwangseok save the world and fight the urge to kill anyone who even slightly annoys him?