After ten years away, Azuma Kazuki returns home, only to be suddenly ambushed and taken captive by a crew of heavily weaponized foes. His rescue comes quickly through his childhood friend Kogane Asabuki, who wields a sentient weapon called a "Bubuki" attached to her right arm. Once freed, Azuma discovers he is also capable of using a Bubuki. With his new allies, he sets off on a mission to rouse the dormant Buranki giant Oubu, buried far underground. Armed with this revelation and purpose, Azuma begins his journey to uncover the secrets behind the Buranki.
