The Linebarrels of Iron story takes place in a fictional alternate future, centering on a junior-high school student named Kouichi Hayase, who escaped his daily life of being bullied as a child by daydreaming about being a hero. His life was forever changed during a class trip in the year 2016 when an artificial satellite fell from orbit. Due to this "accident", Kouichi was left in a coma for half a year, and upon awakening, found himself with strange powers, including superhuman strength. Then, in 2019, a mysterious robot called "Linebarrel" appears before him. It is revealed that the accident from three years ago was not caused by a satellite, but rather by the Machina robot Linebarrel and that this turned him into a "Factor", which is the name given to Machina pilots. This leads him to encounter Emi Kizaki, a mysterious amnesiac girl whose unknown past seems to be related to Linebarrel. He joins her in fighting for JUDA, the world's largest medical equipment maker, which happens to secretly own several other Machina robots.