Yuuki Wakura's life is complicated by the fact that five years have passed since his sister's disappearance during a catastrophic event known as the "Mato disaster." This disaster led to the creation of portals to a dimension called Mato, where monstrous creatures called the "Shuuki" threaten human safety. A Mato fruit allows some women to develop supernatural abilities, resulting in a matriarchal government and a female-dominated organization, the Anti-Demon Corps. Kyouka Uzen, a powerful but underappreciated chief of the Seventh Unit, sees Yuuki as a way to test her unusual abilities and recruits him as her "slave" to fight the Shuuki.