A troublesome yet wonderful journey walking alongside the "Legendary Witch"―― Lean, the descendant of a legendary witch said to have once commanded monsters, saves the life of Hakura, an adventurer. Due to certain circumstances, Hakura is hired as her bodyguard, and they set off on a journey together. The incidents that come to her because of her special powers always involve troublesome monsters, but in reality, the causes often lie not just with the monsters, but with humans as well…. An extraordinary story begins as he walks alongside Lean—a self-confident, selfish, yet somewhat "little devilish" girl who he somehow can’t leave alone.