Yomi no Tsugai  

Daemons of the Shadow Realm, Tsugai of the Underworld, 黄泉のツガイ

In a remote village, there were born two identical siblings, Yuru and Asa. Over time, Yuru became a hunter of animals while Asa was kept in a cage and tasked with carrying out a specific duty that forbade her from interacting with many individuals. One day, on what appeared to be any ordinary day, a group of armed men riding in helicopters, known as "dragons" among the villagers, attacked the village in search of Yuru, killing every adult present on sight. When Yuru tried to meet up with Asa and escape, he discovered her lifeless body instead. The person who had killed her claimed to be Yuru's true twin sister. Before she could capture him, Yuru was rescued by Dera, an outsider who frequently visited the village. However, their rescue was short-lived as they soon found themselves cornered. In a desperate attempt to reveal the truth behind these events, Dera had Yuru give a gift to the deity of the village, which summoned a pair of daemons whose existence was tied to the truth.