This is a story idea where Kyōka Suigetsu decides to leave Aizen and be reborn as a new Zanpakuto spirit of Ichigo Kurosaki after the Hogyoku grants her wish, while only keeping her previous name, gender, knowledge and personality. If someone wishes to adopt this story or make a story based on this story, send me a message.
Inside the inner world of Sosuke Aizen, his Zanpakuto spirit, Kyoka Suigetsu is screaming out in pain, as her master undergoes another transformation in his quest for power, with Aizen having long ago discarded her.
Kyoka curses her master and the Hogyoku with all her being, and wishes to get away from her current master, having been betrayed in the worst way possible for a Zanpakuto.
As her master is now fighting against the substitute soul reaper Ichigo Kurosaki, a fairly tall young man with shoulder-length orange hair. Ichigo catches her master's zanpakuto with his bare hand.
At that moment she hears a voice that she could not identify as neither male or female which asks her:
"Should the opportunity arrive, do you wish to leave your current master?"
Kyoka Suigetsu does not even need to think about it and instantly replies "Yes!"
"Very well. Your wish will soon be granted."
In the outside world, Ichigo Kurosaki knows the only way to vanquish Aizen is to use his ultimate technique known as the Final Getsuga Tensho, so he decides to undergoes an transformation. His hair color changes from orange to black and his hair grows to waist-length, his eyes turn from brown to red, and white bandages cover his upper body, while he is covered in black flame-like energy.
Ichigo knows this technique will cost him his soul reaper powers, using Zangetsu and inner hollow as the sacrifice for this technique, with little hope of ever meeting them again.
Ichigo gathers black flames into his right hand and swings his hand downward, while saying "Mugetsu", sending off a Getsuga Tenshou like energy attack made from black flames.
After Aizen is hit by his technique, Ichigo returns to his previous form, having once again regained his usual shoulder-length orange hair, while noticing that both Zangetsu and his inner hollow are no longer present and knowing that soon his spiritual energy will soon disappear.
Hoping that he has now managed to kill Aizen, he is proven wrong when Aizen suddenly stands up, having survived the attack due to the Hogyoku.
"Impossible!" shouts Ichigo, seeing that his strongest attack be useless against him "You are still alive?"
Suddenly an energy beam not visible to neither Ichigo or Aizen shoots out from Aizen and hits Ichigo in the chest, who despite being able to feel something enter him, is not able to understand what has just happened. At the same time, Aizen's Zanpakuto starts to disintegrate.
"Observe." says Aizen, showing his Zanpakuto to Ichigo "My zanpakuto is fading away, which means that the Hogyoku has determined that I have no longer need a Zanpakuto." as Aizen is about to continue his speech as victor, red spears of light shoot out from his chest.
"Impossible!" shouts Aizen, looking at Ichigo "When did you?", not understanding what is currently happening to him.
Then a man with shoulder-length blonde hair arrives, making Aizen understand what is happening to him, while cursing "Kisuke Urahara!"
While Ichigo Kurosaki and Kisuke Urahara are talking outside with Sosuke Aizen who is about to be soon sealed away, Kyoka Suigetsu tries to make sense of what has happened to her. She is now inside a dark space without light and no longer knows her abilities as a Zanpakuto or her release command, neither does she know her own appearance, she only knows that she is female and that her name is Kyoka Suigetsu, while also having retained her previous personality, and most of her knowledge such as kido and strategy.
As she tries to make contact with her master, knowing she is a Zanpakuto spirit, her voice is not able to reach him, as she is no different from an ordinary Asauchi which has not yet completely turned into a Zanpakuto due to her energy not having fused with her master.
A week after Ichigo Kurosaki has lost all his remaining spiritual energy, his soul starts to stabilize and his spiritual energy starts to slowly return, with his inner world starting to take form, and Kyoka Suigetsu starts to take on an appearance of a beautiful woman.
After about three months, Ichigo's inner world has taken on the shape of a fantasy world, with flying islands with waterfalls, blue skies, beautiful plants, and Japanese style houses, including a big Japanese style castle where a beautiful woman with long black hair and big breasts, who is dressed in a purple kimono, resides. The woman is currently cleaning a Japanese sword while having both of her eyes closed. She then opens her green eyes and asks herself "I wonder if my master is now able to hear my voice?