Azuma Kazuki had been away from home for ten years and had no idea what awaited him when he returned. He had no idea he would be assaulted by dozens of highly armed men and taken prisoner. Fortunately, Azuma's confinement is brief. Kogane Asabuki, his childhood friend, saves him while wielding a bizarre sentient weapon known as "Bubuki" on her right arm. After escaping, Azuma discovers that he, too, possesses the ability to control Bubuki. Together with his new comrades, he must resurrect the Buranki titan Oubu, who is dormant someplace deep down. With this information and purpose, Azuma is set on a new journey to uncover the secrets behind the Buranki.