Kuina Murasame

Kuina Murasame (斑鮫 クイナ（むらさめ くいな） Murasame Kuina) is the client and vessel of Biondetta Shiroyama during the events of the third volume.

Appearance
Kuina is a middle school age girl wearing hot pants and a short-sleeved shirt over a long-sleeved shirt, both of which leave her midriff exposed. On her feet and legs, she wears black knee socks and sneakers. Her semi-long hair is dyed brown. She wears a black leather glove on her left hand, the true form of Girl's Backdoor. She also wears a locket with a thin chain around her neck, which holds a photo of Isabelle's prior identity, Sayuri Kawamo.

Personality
Despite being aware of the wrongness of her actions and feeling guilty about them, Kuina only cares about taking revenge on Government for what they did to Sayuri, since there's no way to save her and turn her back to normal. However, Biondetta has been intentionally fanning the flames of her desire for revenge, and she complained that in the end Kuina had too many things she refused to do for her tastes. Kuina tried multiple times to convince Sayuri/Isabelle to stand down, as she had no desire to harm her or get her involved with her revenge. Similarly, she refused to take the easy way and use Girl's Backdoor on her.

As a child, Kuina was incredibly close to Sayuri, with both of them being close friends who shared everything. The two renewed their friendship after they lost their memories as vessels.

Background
Kuina had been close friends with Sayuri Kawamo since they had been little and they lived in Harukawa City. However, Sayuri was kidnapped by Government and used in their Anthill Project. Kuina was contacted by Biondetta Shiroyama, who revealed Sayuri's fate to her and offered to help her if she wanted revenge. Kuina accepted and the two began to plan against Government.

Light Novel Volume 03
Kuina arrived with Biondetta to Toy Dream 35, with the two soon realizing that their plan to cause a distraction in the city by spreading Girl's Backdoor in advance had failed. However, Kuina refused to abort the mission. The two briefly dealt with some airport workers who tried to stop them from bypassing security customs. The duo attacked Government's Anthill on D Block, facing a group of Pilot Soldiers and the summoner known as Scorpion 11. Biondetta tricked their enemies with an Incense Grenade she'd prepared beforehand, avoiding the attack of the Pilot Soldiers, and then proceeded to quickly defeat Scorpion 11. Biondetta and Kuina discussed Biondetta's insanity and Kuina's desire for revenge while resting in C Block's Chinese restaurant that functions as a meeting place for Illegal. It was later revealed that they had attacked Lu and controlled her with Girl's Backdoor in order to get to Aika and obtain the location of all the city's remaining Anthills. The two continued to destroy the Anthills. Some time later the duo rested in the apartment of a college girl they controlled with Girl's Backdoor, and Biondetta suggested hiring several decoys to spread through the city and keep Government away from them..

While Biondetta met with Kyousuke Shiroyama in a cafe at P Block, Kuina met with Isabelle, who had been placed in advance by Kyousuke in the most likely sniping spot. A fight broke out between the two pairs, and Biondetta's tricks allowed her to cause a chain reaction with the Petals and reach the Divine-class while Kyousuke was still in the Regulation-class, giving her the advantage. However, Kyousuke pointed out that she had wasted a lot of time setting up her strategy, and ordered his vessel to destroy their footing to waste the remaining time of the ceremony and escape. Biondetta managed to survive the fall and was contacted by Kuina. Biondetta then decided to interfere with Government's evacuation plan.

Biondetta infiltrated the Anthill in A Block with ease, as Kyousuke had predicted she would be able to do, and convinced the security chief to change Kyousuke's evacuation plans by appealing to his cowardice by assuring him she would leave him and the VIPs go, as she was only interested in proving her skills as a summoner. Biondetta had obviously lied to him, and she attacked the Stingray he and Maria were using to escape with the Anthill's server. Biondetta and Kuina easily defeated the Pilot Soldiers protecting them, but she was suddenly interrupted by Kyousuke's arrival. Isabelle and Kyousuke revealed to Kuina that Biondetta had manipulated her with Girl's Backdoor and that they had been trying to help her from the beginning. Biondetta used the Girl's Backdoor she had hidden inside her left arm to control Kuina and force her to fight Isabelle, intending to make her destroy her own friend to break Kuina and extend the target of her revenge to the rest of the world. Biondetta engaged Kyousuke, with her tactics once again giving her the upper hand, but Kyousuke managed to take away her domino setup with the support of the pilots of the Stingray, reaching the Divine-class. On Kyousuke's order Isabelle attacked and defeated Biondetta and Kuina. Kuina, who had lost her memories as a vessel after Kyousuke made Biondetta break her contract with her, was finally reunited with Isabelle, believing her new name and look were an image change.

Abilities
Kuina has the talent to be a vessel, though one of the claims she made to Isabelle while explaining the Anthill Project and her former identity implies that it's not particularly strong.