Mercury

Prior to the events of the series, mankind waged a battle of survival against the shadowy creatures of the Grimm. Then mankind discovered the power of Dust, which allowed them to fight back against the monsters.

A web-series anime by Rooster Teeth about four girls who start attending a school for raising Hunters against the Grim and other threats to the fragile peace of the world. Generally considered to be the first "'anime-styled' anime" of the west to go to Japan.