"AHAHAHA!!! GREAT!" Kokabiel caught the serpent by its fangs and he was dragged away for a few tens of meters before stopping. Sona's and Akeno's magic might have been weaker than Rias' individually, but combined and in addition to elemental compatibility, it put Kokabiel into most pressure since the start of this fight.
As strong as it might be, it's only enough to burn Kokabiel's hands a little bit, "Is this all?" After saying those, Kokabiel ripped the serpent into two with only his bare hands and it slowly dissipated into the air, "...N-no way..." Sona and Akeno said at the same time. They both looked towards Aika's direction and noticed that she closed her eyes and a strange aura is emitting from her. They also noticed that Koneko already disappeared from her position and they suddenly heard Kokabiel's shocked voice, "What!?"
They looked back and saw Kokabiel flew backward and hit the wall of the school building, going through it and hit the barrier he coughed up blood and all of them saw Kokabiel's chest caved in, 'What just happened!?' All of them are asking inside their head.
"Koneko!" Rias' voice woke them up and looked at the former spot where Kokabiel is standing just now. Koneko, in her nekomata form, is laying on the ground unconscious with blood coming out from her orifices. Asia, already bawling, hurriedly ran over to her spot to immediately heal her.
What happened just now is just a few microseconds after Kokabiel ripped Sona and Akeno's magic, Koneko, in her nekomata form with her ears and tails caught in white flame, Flash Stepped in front of Kokabiel. Koneko threw a punch and normally, Kokabiel could have easily blocked it but to his shock, her fist instantly accelerated and reached his chest. The attack resulted in his caved-in chest and pretty much-destroyed lungs.
Koneko's attack isn't a normal punch but a Hakuda technique that Yoruichi taught her called Ikkotsu (Single Bone) that focuses all of her strength into her fist and transfer it to the target's body to wreck it. Yoruichi taught her this to serve as the secret technique that she can use in desperate times. Although she did that much damage to Kokabiel, she hasn't mastered the technique at all, resulting in her entire right arm that she used invalid and not being able to kill Kokabiel who doesn't have much defense in the first place.
After such an attack, Koneko dropped down unconscious and convulsing with blood all over her face. Her internal wounds worsen and a failed use of Ikkotsu made it worse. Asia's healing is helping a lot but it's only enough to keep her state from further deterioration.
"Kah! Kah!" Kokabiel coughed out blood and his body already started healing. Despite the grave look of his injury, it's far from fatal for beings of his caliber. He gave Koneko a surprised look after inspecting his injuries, "What was that just now?" Still not believing what just happened, Kokabiel asked. He couldn't get how he was suddenly hurt and the power of that punch is off the charts for a Low-Class Devil like her.
Kokabiel wanted to finish off Koneko because he felt threatened by her but before he could do so, another thing caught his attention and those around.
The air around Aika became heavy and started swirling. The next moment, a pillar of bluish-white light ascended from her and her tattered school uniform slowly change into a black and white attire. The attire is composed of a white shitagi, a black kosode and hakama, a pair of white tabi, a pair of waraji, and a white obi(sash). A shihakusho, uniform worn by all Shinigami from Gotei 13. Along with her transformation is a two-meter long nodachi materializing behind her.
What shock those around her, however, is not her appearance nor her nodachi, but the aura she's currently emitting now. It's far from the Human aura she's radiating until now and it's giving them chills, the fearful kind. But they couldn't also point out what kind of aura is this as this is there first time feeling this kind of aura, except for Sona and Akeno, of course.
Kokabiel is once again, dumbfounded at what is happening. His vast experience and common sense couldn't keep up with two 'unnatural' beings, namely, Koneko and Aika, "What are y-- !?" He tried to ask a question again but Aika disappeared and reappeared in front of him holding her nodachi high up and threatening to bisect him into two. Fury is very obvious on her face, "Your enemy, obviously!"
Aika brought down her nodachi with all her might and Kokabiel immediately responded by conjuring two swords made out of light to block her attack. Kokabiel successfully met her nodachi but to his dismay and shock, just after a few seconds of the struggle between them, her nodachi went through his swords. Kokabiel jumped back to avoid her nodachi's trajectory but he was still cut from her right shoulder until his left waist, "Kuh!!!" Using this chance, however, Kokabiel kicked Aika away while she's trying to recover her stance from the attack. Aika blocked his foot with her nodachi but she was still sent flying away and made a hole through the wall of the school building.
"Aika!" Sona exclaimed and she left Koneko's side and ran towards her, "Aika! Are you alright!?" Sona used her remaining magic to remove the rubble that is pressing on Aika.
"I-I'm fine... Just a little bit dizzy..." Aika stood up with Sona's help and touched her head, 'Feels damp... Crap... I'm bleeding!' She looked at her hand and saw a splash of blood on it.
"You aren't okay at all!" Sona also saw her hand and shouted at her. Sona gritted her teeth and grabbed Aika's face towards her. Meeting her eyes directly, Sona pleaded, "Aika... Take those who are important to you away and escape from this town."
Aika looked at her for a bit before giving her a big smile, "I doubt those important friends of mine would agree to go with me, so no~!" Aika separated from Sona to meet Kokabiel who already closed his wounds using her Holy Power.
Sona stared at Aika's back blankly for a few seconds before understanding what she meant. She clenched her fist and gritted her teeth, 'Where is that bastard when you need him the most?...' But she immediately shook her head the threw those thoughts away, 'No... It's better that he's not here... He might just die with us...'
"Who are you?" This is the first time Kokabiel made a grave face. Although he has been holding back a lot to gain more amusement from this fight, repeatedly getting thrown around couldn't make him laugh at all. Especially this girl who he thought just a normal human but turns out to be a different existence that he never met before, thus, his question.
Aika let out a big grin and put her nodachi over her shoulder before replying, "Aika Kiryuu U.S. #3~."
"What...?" Everyone couldn't make sense of what she's saying.
Seeing Kokabiel's and other's confusion she explained, "Well, I'm just a regular employee from the Urahara Candy Shop on the outskirts of the town."
"Urahara Candy Shop?" Kokabiel only thought that it was a quirky name from a quirky character as those individuals aren't very rare, "What is your organization's goal?" He wanted to know what he dealing with first and why would she involve herself with the Devils, 'She's clearly isn't a human... Where did she come from?'
"Duh~! Of course, it's to sell as much candy as possible! Are you dumb? Didn't I just say that I'm an employee in a candy shop?" Aika rolled her eyes on him.
Kokabiel temple throbbed after hearing her, "...Are you mocking me?"
"Oh~! You finally got it, you clever oaf?" Aika pointed her nodachi at him with a large grin. At this point, she's only trying to rile him up to see more openings.
"You bitch!!!" And it's a great success.
"Round two, then." Aika took a deep breath again, "Aeternam Somnium."
"Huh? Why are you calling the name of your Sacred Ge-- !?" Before Kokabiel could finish his, however, Aika's aura rose up to terrifying levels, but instead of bluish-white light from earlier, she's now releasing a swirling black and red pillar of light. It only took few seconds before the pillar disappeared again and Aika's nodachi change into black and red inverting color twin single-edge swords.
"Round two, start!" Aika disappeared from her position and appeared on top of Kokabiel's head, blasting a wave of black and red energy to him.