Black Rock Shooter originated as an animated music video by Supercell. The OVA adaptation features the eponymous character and tells two stories. The first takes place in the normal world, where Mato starts her first day of junior high. There she becomes fast friends with Yomi, although this friendship becomes strained as time goes on. One day, feeling alienated, Yomi mysteriously disappears. The second story takes place in a dark fantasy world, where a young girl does battle against an unnamed nemesis.