In the year Tenpo fourteen, Yoi—creatures from another realm—raid Edo. Those who confront them belong to the Bansha Aratemesho. Publicly, Bansha Aratemsho is portrayed as a society that researches foreign tomes. In reality, it is devoted to annihilating the Yoi and other threats. Its fighters are known as Ayakashi. They collect reports of bizarre incidents across the nation and dispatch to eliminate any Yoi that surface. Their ranks are oddly eccentric: a man who has forgotten his past, a woman who adopts male attire. Each wields unique abilities to vanquish the Yoi. Their secret gatherings are shrouded in mystique at night.