Five years ago, the 300-year-long war between the alliance of six nations and the Gaz Empire came to an end as Emperor Arthur Gaz was finally killed by eight warriors known as the Eight Heroes. The Empire's lands were divided by the alliance, who later formed the Council of Six Nations to bring peace and order to the land. In the present, Toru Acura is an unemployed Saboteur (乱破師サバター Sabatā) who is unable to settle in this peaceful era as there is no demand for his Saboteur skills, and thus he sees no meaning in his life. While out foraging in the forest, Toru encounters Chaika Trabant, a white-haired Wizard (魔法師ウィザード Wizādo) who travels with a coffin. After saving her from a man-eating unicorn, Toru, along with his sister Akari, is hired by Chaika to gather the scattered remains of Arthur Gaz. It is revealed that Chaika is the former Emperor's daughter, who managed to escape in the chaos following her father's death and wishes to find her father's remains so that she can give him a proper burial. Over the course of the series, the group faces difficulties as each of the Eight Heroes has kept their share of the Emperor's remains to harness its magic energy. Frederica, a shape-shifting dragoon, joins their party. Meanwhile, the six nations sends the Kleeman Agency's Gillett Corps to hunt down Chaika to obstruct their quest in order to prevent another war. Other groups led by girls claiming to be Chaika Gaz also pursue them to take their parts.