Incomplete Girls

The mysterious hooded figures are other selves created by Black★Gold Saw.

Black★Rock Shooter (2012)
Black★Gold Saw creates the hooded figures by pouring water droplets from a watering can onto the ground, from where they sprout. Black★Gold Saw takes an interest in Arata Kohata's "other self".

Black★Rock Shooter breaks into into the area, presumably killing a good chunk of the hooded being. BRS attacks Black★Gold Saw but misses, hitting and disabling most of the hooded figures. Black★Rock Shooter approaches Arata's other self and holds her hand up to it. However it trembles in fear and rejects the offer. As a result, Black★Rock Shooter beheads the being. In the real world, Arata kneels over in pain. The incident was sensed by Mato Kuroi and Saya Irino.

Black★Gold Saw uses her watering can to summon more hooded beings in her battle against Insane Black★Rock Shooter. Some of these hooded figures have horns, and are armed with pitchforks. They attack Insane Black★Rock Shooter, but she easily defeats them before turning her attention back to Black★Gold Saw.

After Insane Black★Rock Shooter's defeat, the hooded figures, including Arata's, come back to life. As a result, Arata regains her memories and feelings for Takuu. The hooded figures now seem to be taller, about the same height as the main characters' other selves, which implies that they have become stronger.

Trivia

 * Their blood is completely black.
 * They may be incomplete "other selves", as they seem to be significantly weaker than the main cast's "other selves" and they do not seem to have a complete form or personality.
 * In Episode 7, it is implied that most other selves are more advanced or more powerful hooded figures; during Strength's flashback, several other selves are portrayed as hooded figures with a more developed appearance, similar to Strength and B★RS. Additionally, both Strength and B★RS wear similar hoods.