Being a magician Kuroha has the power to destroy any inanimate object, as well as transferring power when in direct contact with organic beings. Her power is so strong that while being in the lab, she had to undergo multiple extensive tests. As a result, Kuroha has almost completely forgotten her childhood memories, with only a few bits of emotion lingering.
Although usually gentle and caring, she can be short-tempered when embarrassed. She easily gets jealous when Murakami is "too close" to other girls (especially when Kazumi is seducing Murakami) and she would use her magic to destroy things around unconsciously. She is very puzzled by this reaction.
Kuroha is actually Murakami’s childhood friend "Kuroneko", who was assumed dead when tried to save Murakami from falling into the dam. Murakami later found the truth by identifying the three moles near her armpit.
Kuroha was numbered 7620 when was in the lab. She was the first Valkyria that has S-ranked power which suppressed the current Valkyria: Fujisaki Mako. However Kuroha gradually lost her powers and memories over time, and was ranked down to B Rank and about to be wasted. Nanami also mentioned to Murakami that if the third button on Kuroha’s neck was pressed, she may regain her power with 99.9% of risk to die.
During the final fight between Kuroha and Mako, she was nearly killed for covering Murakami from Mako’s attack. Out of desperation, she pressed her third button and brought back the powers and memories of "Kuroneko". The revived Kuroha, now regained all her memories, expressed her happiness for able to reunite with Murakami, her personality was also changed.
After a ferocious fight, Kuroha defeated Mako with micro black hole power, but lost all her memories up to the point and most of her powers. After a month, she hasn’t regained any bits of memory and treats Murakami like a stranger.