A 10th grade student. Born as Shirone, Koneko is a young Nekomata who is part of a rare species among her kind, called the Nekoshou. After losing her parents, she and her older sister, Kuroka, were later taken in by an unnamed Devil who reincarnated her sister as one of the members of his peerage. However, Kuroka’s power as a Nekomata supposedly soon grew out of control, eventually causing her to kill her master and become a Stray Devil on the run from her pursuers. In actuality, he had planned to harm Koneko, causing Kuroka to kill him in order to protect her younger sister.
She doesn’t show any emotion at all, and says harsh things and hits Iseei when he is doing or thinking something perverted. She shows the most concern for her comrades when they are in trouble.
Despite her petite size, Koneko boasts a lot of physical strength and endurance, a standard of the Rook. She can lift heavy objects and throw them as weapons with little effort. Also, enemy attacks have been known to bounce right off of her, including light-based weapons that would seriously wound or kill a regular Devil. After her identity as a Nekomata was revealed, it was further revealed that she can use Senjutsu and Youjutsu but is not fully proficient in using them as compared to her sister. Koneko has the potential to become an even more powerful user of Senjutsu and Youjutsu than her older sister.
Following the incident and the failed manhunt that came after, Koneko was sentenced to death by the Devils in hopes of preventing another incident like Kuroka’s from happening. However, Sirzechs Lucifer, one of the Four Great Satans, protected her, and left her under his sister’s, Rias’ care. Due to the trauma she experienced with her sister’s murder and betrayal, she fell into a deep depression, eventually robbing her of nearly all of her emotions until Rias helped her out of it. It was around that time Rias gave Koneko her name, and made her her servant.
She refused to use the power of Senjutsu because she didn’t want to become like her sister. She learned to accept her powers along with Akeno after Issei helped her overcome her own fears. After that, she stops being harsh towards Issei, her feelings teeter towards open affection and she begins to take naps while laying on his lap, much like a cat.