Japan, 1716. The Tokugawa shogunate has established a secret organization called the Oniwaban to manage the escalating problem of monster attacks on Edo. Eleven years later, in a distant village far from the capital, a girl with an unsettling ability — she sees a black thread whenever a disaster is about to occur, her predictions always accurate — has been driven out into the snow by terrified villagers. Members of the mysterious Oniwaban find her there and tell her she is needed in Edo. The power that has brought her nothing but misfortune is about to become one of the organization's most valuable assets.