A godlike entity of immeasurable power. Because its voice takes the life of any mortals who hear its song, it is feared and revered as a manifestation of Death.
Taking the appearance of a human female with silver hair and red eyes, this Grim Reaper seems to only be active at night.
On rare occasions, they are said to side with humans. Some speculate that, behind every major event and influential person throughout the course of history, there has been a Valkyria pulling the strings.