"I'll use you," the beautiful demon Kume said with a mysterious smile. After the death of her foster father, Tsukishiro lost her ability to speak, and because of a certain ability, she was viewed with dread and persecuted by the villagers in her village. With a mysterious song, Tsukishiro was able to put to sleep beasts called Moke, which possess a dangerous miasma. However, she was treated like a villager's possession and forced to accompany the men on dangerous Moke hunts. One day, a beautiful demon named Kume appeared before Tsukishiro, in human form but able to control miasma. He told Tsukishiro that he had come to repay a debt and would grant Tsukishiro's wish... As the lullaby connected lost memories, the demon and the girl, and the promises of the past, the destinies of the two began to change.