Junkyard is a group of engineers who give life and purpose to things that have been destroyed and discarded. Serpent Tail is a mercenary unit that fights on behalf of the powerless. Row Gheul and Gai Murakumo, who both handle Astrays, are good friends and rivals! However, Serpent Tail receives a request for a mission from a mysterious person called "Limitless." That mission is to "eliminate Row Gheul"...!?