Daemons of the Shadow Realm

Daemons of the Shadow Realm (黄泉のツガイ, Yomi no Tsugai) is a Japanese manga series written and illustrated by Hiromu Arakawa and published in Square Enix's Monthly Shonen Gangan.

Plot
Yuru is a boy who lives in a remote mountain village, spending his time hunting birds and being one with nature. But one day, Yuru's younger twin sister Asa is called to serve in the jail at the heart of the village, her duty also confining her there. Yuru slowly unravels the unnatural mystery hidden beneath his quiet village.