In a secluded village, twin siblings are born, destined to separate their lives into day and night roles. As time passes, the elder twin, Yuru, grows into a capable hunter of animals, while his sister Asa remains confined within a cage, entrusted with an enigmatic duty that cuts her off from most villagers.
One seemingly ordinary day, military forces descend in helicopters—referred to by the locals as "dragons"—and launch an assault on the village, focusing on the adults and specifically hunting for Yuru. Racing to find Asa so they can escape together, Yuru discovers her dead body, and the killer declares herself to be his real twin sister.
Just as this woman is about to capture Yuru, Ryuu "Dera" Tadera, a frequent guest in the village, steps in to rescue him. Their getaway does not last long, however, and they quickly find themselves in a desperate predicament. With no other option, Dera carries out a rite, invoking the village's god to bring forth a pair of daemons—their emergence prophesied to unveil the mysteries behind the settlement's turmoil.