Upon reincarnation into an alternate world, mecha enthusiast Ernesti Echevalier (Eru) discovers his greatest aspiration within grasp—commanding the legendary Silhouette Knights, towering humanoid weapons of devastating power. Together with childhood friends Archid Walter and Adeltrud Walter, Eru embarks on an ambitious path to become a Knight Runner, an elite pilot of these magnificent mechanical war machines that hold dominion over the realm.