KAEDEGAMI

A secret relationship with a mysterious entity... In a world with demonic monsters called Shenguai, a young orphan named Kou lives alone in the mountains with a mysterious Shenguai named Chiyou. But Chiyou has a tragic past, and Kou will have to give all of himself in order to save her. A beautiful East Asian adventure now begins! (Source: MANGA Plus) — Description from AniList community (anilist.co).