After his sister's disappearance in a catastrophic event known as the 'Mato disaster,' Yuuki Wakura embarks on a journey five years later. In Japan, the emergence of portals to a demon-infested realm called 'Mato' has led to the rise of the Anti-Demon Corps, a female-led organization wielding powers from the Mato fruits. When Yuuki gets trapped in Mato, he is rescued by Kyouka Uzen, the head of the Seventh Unit of the Corps. Tasked with unlocking her unique abilities, Kyouka enlists Yuuki's help in defeating the monstrous Shuuki, binding him to her as a servant in a perilous fight for survival.