Former prince of the Arcadia empire, Lux, inadvertently enters a female dormitory's bathing area and catches a glimpse of the newly crowned princess Lisesharte in the nude, angering her. Consequently, Lisesharte challenges him to a Drag-Ride duel.
The Drag-Rides are an antique set of armored mechanical weapons that have been discovered in ruins across the globe. Lux was once known as the most powerful Drag-Knight, but his unwillingness to fight in combat has earned him the title of "undefeated weakest" Drag-Knight. Following his confrontation with Lisesharte, Lux enrolls in an all-girls academy that instructs royals on how to become proficient Drag-Knights.
