The story follows a young man who writes unpopular web novels to support his sick mother. One day, after accepting a mysterious contract, he suddenly finds himself reincarnated into the world of his own creation, Heroic Chronicles of the Overlord King.

However, he is not reborn as the main hero but as a minor side character named Attila. To survive in this harsh new world, Attila fights alongside his father, the tribal chief Munzuk, taking part in inter-tribal conflicts and gradually rising to prominence through many battles.

While searching for a way back to his original world, Attila continues along the path of the original story, leading a mercenary army through fierce wars and winning victory after victory. Eventually, he faces and defeats the novel’s original protagonist, Charles, gaining fame and recognition. But his actions begin to distort the history of the world he once wrote.