Progress Was Too Slow
"Cooperation?" Aizen narrowed his eyes and stared at Tsuna. "I don't think there's anything we can cooperate on."
"Just mastering a little bit of the Hogyoku's power has made you this arrogant?" Tsuna down in a chair, somewhat puzzled. This Aizen was quite different from the elegant and calm image he remembered.
Aizen's act of creating chairs in front of them was a demonstration that he had mastered the Hogyoku. He used the Hogyoku's ability to materialize the host's thoughts to give Tsuna and Aizen a small show of force.
"A little? What are you talking about? I've already merged with the Hogyoku!"
Just like when Tsuna first arrived at Las Noches, a spiritual pressure emanated from Aizen and pressed down on the two of them. Sensing the change in Aizen's spiritual pressure, Tsuna slightly understood Aizen's current state of mind.
Before obtaining the Hogyoku, he had to keep a low profile and be meticulous in his calculations. After acquiring the Hogyoku, if he still had to be cautious and calculating, wouldn't the Hogyoku have been obtained for nothing?
No wonder the final fused Aizen still couldn't defeat Ichigo. Did the Hogyoku amplify Aizen's negative emotions, or was this simply Aizen's true nature?
It has to be said that Aizen's life was indeed quite good after obtaining the complete Hogyoku. In addition to merging with the Hogyoku and gradually breaking through in strength, he also found great pleasure in using the power of the Hogyoku to casually turn Hollows into Arrancar.
That enlightenment process allowed Aizen to experience the authority of a god for the first time, making him yearn even more for the throne in the sky, to ascend it, and then to rule over all living beings.
In response to Aizen's questioning, Tsuna flipped his hand, and a small arrow, about the size of a chopstick, shot towards Aizen. It was Spirit Bow that Tsuna himself had conjured, only the size of a palm, which Ryūken jokingly referred to as having no talent.
The Spirit Bow and Arrows wasn't particularly powerful, but its advantage lay in its surprise attack, which was enough to achieve Tsuna's goal.
"This little thing thinks it can hurt me?"
Aizen held the Spirit Bow and Arrows between two fingers; it was just a hair's breadth away from piercing his chest. However, as soon as he finished speaking, the Spirit Bow and Arrows exploded.
The force of the explosion was no match for Aizen, but it was enough to blast a large hole in his clothes. On his chest, a blue -Aizen purple sphere was embedded in a cross-shaped crack, with fine, dense blue-purple lines resembling blood vessels along the edge of the crack.
That was the Hogyoku. With the Hogyoku embedded in his chest, Aizen had completed the initial fusion with Hogyoku. He believed that his strength at this stage had surpassed the combined strength of the Espada, which was perhaps the source of his confidence in going berserk.
"Sawada Tsunayoshi, did you make a special trip to Hueco Mundo just to see the Hogyoku?"
Aizen nonchalantly patted his chest, brushed the tattered cloth from the explosion off his body, and then casually opened his clothes.
"Just say you want to see it. You are qualified to witness the power of the Hogyoku."
Tsuna covered his eyes speechlessly. He only wanted to see how far Aizen had fused with the Hogyoku, but he had no interest in Aizen's physical body, let alone Aizen pulling open his clothes in front of him.
It's absolutely an eyesore.
Tsuna didn't mind clothes being torn due to battle like Ichigo's; what he couldn't stand was a grown man deliberately displaying his body in front of him. Okay, he was just displaying the Hogyoku.
Unlike Tsuna, Urahara Kisuke's eyes were fixed on Aizen without blinking. To be honest, he was very interested in the Hogyoku's biological fusion experiment. If he weren't afraid that Aizen might have the idea of destroying Soul Society, he would have already joined forces to study it.
Tsuna had to probe the progress of Aizen's fusion with the Hogyoku, information that even Sora Inoue was unaware of.
But after seeing that Aizen had only embedded the Hogyoku in his chest, Tsuna couldn't help but feel disappointed. Aizen in this state might be strong to others, but in Tsuna's opinion, it was far from enough.
"Your progress is way too slow!" Tsuna's tone was filled with undisguised disappointment.
Aizen's face froze for the first time. To maintain his image as the King of Hueco Mundo, he could only forcefully keep a straight face. "What do you mean?"
"I deliberately gave you so much time, and you've only reached the first stage of fusion. Are you really Sosuke Aizen? Or have I fallen for Kyoka Suigetsu again?"
Of course, Tsuna wasn't under the Illusion of Kyoka Suigetsu or not. He was deliberately playing hard to get with Aizen, that genius Bleach from Soul Society, who had only completed the first stage.
"What do you know! I've already started my journey towards breaking through to the Bleach dimension!" Aizen said coldly. The fusion with the Hogyoku allowed him to feel a long-lost increase in strength, which undoubtedly proved that his path was the right one.
"Yes, breaking through the Bleach dimension, borrowing the power of Hollows and Bleach, and starting to evolve under the impetus of the Hogyoku, eventually becoming a higher dimension and completely mastering the power of Bleach."
"The so-called power of Bleach is the Zanpakuto, and the sign of a complete breakthrough is fusion with the Zanpakuto. Where is your Zanpakuto? Don't tell me that Kyoka Suigetsu is already inside you."
This time, Aizen's expression completely crumbled. Tsuna had condensed his future evolution into two sentences: "How did you know, Zanpakuto fusion?"
"Is it possible that I've found an alternative method to fuse Bleach and Zanpakuto?" Tsuna looked at Aizen with amusement. "Without Hollows or the Hogyoku, the Bleach themselves can obtain power greater than the current Bleach, Zanpakuto fusion?"
"Impossible!" Aizen's immediate reaction was to question it, but he quickly realized something, "Those two powerful spiritual pressures in Soul Society, could they be from you?"
Even after arriving in Hueco Mundo, Aizen didn't forget to gather daily intelligence about Soul Society, and he noticed Tsuna's two uses of power Beyond Bankai.
One instance was when he used the Cloud Attribute's Beyond Bankai during his battle with Genryūsai Shigekuni Yamamoto. At that time, he was sealed by a barrier, Aizen only sensed a strange yet powerful spiritual pressure.
The second instance was when he fought against Genryūsai Shigekuni Yamamoto's clone Beyond Bankai Rain attribute. At that time, there was indeed no barrier to protect him, but Aizen's Surveillance Spirit Bug were crushed by the immense spiritual pressure, which was like the ocean, in an instant. They only had time to transmit the information about the terrifying spiritual pressure.
Because he hadn't personally witnessed it, Aizen could only speculate based on data and was unaware that Tsuna had already mastered a level Beyond Bankai.
"Ah, it's just Zanpakuto fusion. It's a common technique in Soul Society; every Captain-level Bleach trains it." Tsuna left out half of what he was saying. Training is one thing, but whether one can actually succeed is another matter entirely.
Aizen's face twitched slightly. When did Zanpakuto fusion become a common technique among the captains of Soul Society? He had never heard of such a thing when he was alive.
"Did you bring it to Soul Society?" There's only one possibility: it was Sawada Tsunayoshi who brought it there the first time he went to Soul Society.
"It's not about bringing it; it's a feasible method. It's about gaining the complete approval of the sword spirit and allowing the power residing within the Zanpakuto to return to the Bleach itself. That's what's called Zanpakuto fusion," Tsuna summarized simply.
"Sword spirit? I didn't expect you to be so naive, Sawada Tsunayoshi." Aizen scoffed at Tsuna's words, remaining steadfast in his belief that his path was the best way to gain greater power.
"Aizen, you don't have a sword spirit, do you?" Suddenly, Urahara Kisuke, who had been silent all along, interjected, "Or perhaps you've completely erased the sword spirit's intelligence?"
Having fought Aizen for over a hundred years, Urahara Kisuke has his own understanding of Aizen's personality. In his view, Aizen is undoubtedly a powerful person, so powerful that he wants to control everything, including the disobedient sword spirit.
As is well known, in the Blade Zen training of Bleach and Zanpakuto, the sword spirit is a very important existence. Only by listening to and understanding the name of the sword can one gain greater power.
If the Bleach fails to satisfy the sword spirit, the sword spirit will conceal part of its power, and will not even tell the Bleach its name, let alone use its Shikai and Bankai.
The fact that the Decimo Zanpakuto resided within Tsuna Zanpakuto already enough to surprise Urahara. He had never seen a sword spirit unconditionally trust its master and directly hand over the power of its Bankai to Tsuna.
"Heh, you're mistaken, Urahara Kisuke..." Aizen chuckled coldly. "I've never done anything to Kyoka Suigetsu, unlike you and Kurotsuchi Mayuri, who have never stopped modifying their Zanpakuto, have you?"
Aizen reached behind the chair and pulled out Kyoka Suigetsu, saying, "The so-called sword spirit is merely a tool used by Bleach in their Blade Zen training. Shikai and Bankai are just Bleach's process of self-discovery."
"As for the sword spirit of Kyoka Suigetsu Water Moon, it disappeared after I mastered Bankai, because I have an absolutely clear understanding of myself and no longer need any sword spirit to pave the way for me!"
A look of overconfidence bordering on arrogance appeared on Aizen's face. This was what set him apart from other Bleach. From the moment he stepped into Bankai, his Kyoka Suigetsu could no longer restrain him.
Hearing this, Tsuna finally understood why Aizen sought the Hogyoku as a way to break through the limits of Bleach. Without its spirit, Kyoka Suigetsu was merely a tool in Aizen's hands. A cold, lifeless tool could not possibly resonate with its master and unleash power Beyond Bankai.
Perhaps this is the limitation of Kyoka Suigetsu. Although Aizen's powerful spiritual pressure created Kyoka Suigetsu Kyoka Suigetsu, its Complete Hypnosis is still too powerful no matter what.
Once the master of Kyoka Suigetsu has mastered Bankai and maintained absolute clarity of mind, the sword spirit of Kyoka Suigetsu will disappear, meaning that its master will have no further room for advancement.
This might be the Kyoka Suigetsu to the superstructure that was closed in order to open the door to Complete Hypnosis.
If Tsuna's prediction is correct, Aizen and Kyoka Suigetsu complemented each other perfectly.
However, Aizen's talent was simply too great. The price of Kyoka Suigetsu, which lacked a sword spirit, became the Chains that bound Aizen.
For other Bleach, not having a sword spirit wouldn't be such a bad thing. For an average Bleach, Beyond Bankai is a power they can never reach in their lifetime.
Through his research on the Hogyoku, Aizen forged his own path of Zanpakuto fusion.
This path coincides with Tsuna and the others' Beyond Bankai, except that the Bleach are now training to reforge their swords in their inner world using Bleach power and a small amount of Hollow's power.
Aizen, on the other hand, directly combined the power of Bleach and Hollows in order to break through to a higher dimension. He used himself as the material for forging the Zanpakuto and forcibly achieved fusion through the guidance of the Hogyoku.