Dark Blade

About
When Noroi and the Dragonian turn into the same being, and that being has sex with a Blade who has grown to despise humans and adore Noroi, the combined energies turn her into a Dark Blade, a terrifying creature far outclassing normal Blades. Though their body looks the same, they have completely forsaken their humanity, reveling in slaughter and rape. They can kill hundreds of people effortlessly, and will display sadistic glee while doing so, with their only remaining affection lying towards Noroi himself.

During the events of Beat Blades Haruka, both Haruka and Narika can turn into Black Blades in the Brutal Route endings, Haruka in Black Awakening (Normal) and Narika in Eternal Black Love (True), though the latter probably becomes one in Black Awakening as well.