The Garos are a Tibeto-Burman ethnic group in Meghalaya, Nagaland and neighboring areas of Bangladesh like Mymensingh, Netrokona, Jamalpur, Sherpur and Sylhet, who call themselves A·chik Mande (literally "hill people," from a·chik "bite soil" + mande "people") or simply A·chik or Mande. They are the second-largest tribe in Meghalaya after the Khasi and comprise about a third of the local population. The Garos are one of the few remaining matrilineal societies in the world.
Kaoru Mitsuki, a struggling artist with a string of bad luck and an uncanny ability to cycle through different occupations incredibly quickly. When she is accidentally splashed with the blood of a Horror, it leaves her tainted and with one hundred days to live. The law of the Makai Knights dictate that she should be struck down, but Kouga decides to leave her alive as bait to draw out other Horrors. Thus, Kaoru is pulled deeper into the taboo underworld of Makai Knights and Horrors, and into the life of Kouga Saejima.