After killing the grotesque blue monkey Arrancar, Raizen Kō followed the same method Oi Rimi had used earlier to open the Senkaimon. Without hesitation, he stepped through the gateway, beginning his return journey to Soul Society.
Raizen Kō felt quite satisfied with the results of his first true Shikai battle. Although he had heard the call of his Zanpakuto from the very first moment he held the Asauchi that Madarame Ikkaku had obtained for him, this battle was the first time he had truly fought using its released form.
Even now, his understanding of how to wield Annihilation God was still at a very preliminary stage.
However, one thing was absolutely certain
The potential and upper limit of his Zanpakuto were extraordinarily high, and this realization filled him with quiet confidence and excitement.
...
At the same time.
Deep beneath Seireitei, inside the Great Spirit Book Repository located under the authority of Central 46.
Aizen Sōsuke, dressed in his Captain's haori, stood calmly beside Tōsen Kaname and Ichimaru Gin. The three of them had secretly observed the entire battle between Raizen Kō and the blue monkey Arrancar in real time, using a projection system hidden within the Repository completely unknown to Central 46.
"Ito Makoto… no, Raizen Kō," Aizen murmured with a faint smile, adjusting his glasses lightly. "What an interesting Zanpakuto."
Tōsen Kaname spoke in a low voice. "Lord Aizen, the results of this Arrancar creation experiment are more successful than before. However, there are still instabilities."
Ichimaru Gin narrowed his eyes as usual, his fox-like smile never fading. "Fufufu… looks like the boy is more dangerous than expected."
Aizen said nothing more, merely watching the recorded battle replay silently, his expression thoughtful.
...
Several days later.
Inside the Shinigami Armory of Seireitei.
"All the unowned Asauchi in Seireitei are stored here. At present, there are more than nine hundred blades in stock. Take your time. You are bound to find one that resonates with you. Remember choose with your heart."
Sanada Yūsuke, the elderly Shinigami in charge of guarding the armory, spoke patiently as he guided Raizen Kō through the massive weapon vault.
Standing nearby, Madarame Ikkaku and Ayasegawa Yumichika waited quietly, arms folded, clearly bored but unwilling to leave.
Raizen Kō gazed at the twelve enormous cabinets before him, each filled with dozens of neatly arranged Asauchi.
Most of the swords followed the standard design used throughout the Gotei 13. Only a few displayed minor variations—slightly longer or shorter blades, differently shaped tsuba, or unique patterns along the hilt.
Raizen Kō slowly walked around the cabinets several times, examining each blade carefully.
Finally, he stopped, closed his eyes tightly, and began to focus inward.
He attempted to communicate with the power that existed deep within his soul the presence known as Annihilation God.
The so-called release of a Zanpakuto, whether Shikai or Bankai, was in essence the manifestation of a Shinigami's own soul power.
The Asauchi merely served as a medium to draw out and give form to that inner strength.
Shikai and Bankai were simply different stages and degrees of that manifestation.
Therefore, Raizen Kō closing his eyes and connecting with his inner power was equivalent to allowing Annihilation God itself to choose its own vessel.
Gradually, his awareness faded.
The world around him seemed to spin and distort.
When Raizen Kō opened his eyes again, he suddenly found himself standing within a dim and familiar forest.
A towering figure stood silently before him.
"Is this… the Great Hollow Forest?"
Raizen Kō was startled to realize that he was here in a human form.
"No… this is merely my inner world."
In the next instant, understanding dawned upon him, and he looked once more at the figure before him.
It was a massive, imposing silhouette tall and muscular, its entire body jet black. Dark golden lightning patterns crawled across its skin, extending all the way to the mask covering its face.
The bone-white mask stretched backward, connecting seamlessly with the grotesque centipede-like armor that covered its spine.
"The manifestation of my soul power… is actually in the form of my main body?"
At first, Raizen Kō was stunned.
But after a moment of thought, he immediately understood.
This clone was created from the main body and shared the same consciousness. It was only natural that the core essence of his soul would take on the same form.
"You've finally come."
The figure spoke slowly.
More accurately, it was not truly the main body speaking, but the personified spirit of his Zanpakuto Annihilation God.
...
Back in the real world.
Within the armory, Raizen Kō opened his eyes once more.
Guided by the call deep inside his soul, he walked directly to a cabinet in the front left corner and selected a completely ordinary-looking Asauchi.
It was identical to the swords used by most Shinigami of the Gotei 13.
The only distinctive feature was the long, thin crimson threads wrapped around the tsuka-ito of the hilt.
"Is this your choice, Annihilation God?"
Raizen Kō examined the unremarkable blade with slight confusion.
Yet since Annihilation God itself had chosen this Asauchi as its vessel, there had to be a deeper reason.
"Ahh, finally done?" Madarame Ikkaku yawned loudly, leaning lazily on his Zanpakuto. "Let's hurry back already. Captain Zaraki is waiting."
"Sorry, sorry," Raizen Kō replied with an apologetic smile. "Ikkaku-senpai, I'm ready now."
He had indeed taken quite some time to complete the selection.
After Sanada Yūsuke escorted the three of them out of the armory, he carefully sealed the massive door.
"Seal!"
The old Shinigami formed a complex hand seal and activated a special form of Kidō upon the reinforced entrance.
Once finished, he turned back to Raizen Kō and offered a few final words of advice.
"If in the future your Asauchi is damaged beyond repair, you may apply to come here again to select a new one."
"However, under normal circumstances, as long as you are properly in tune with your Zanpakuto, any damage it sustains in battle can be repaired naturally using your own spiritual power."
"The same applies to Shikai. Even if it is damaged, it can recover by absorbing Reiatsu from its master."
Sanada Yūsuke paused, then looked directly into Raizen Kō's eyes.
"But you must remember this above all else."
"Once you master Bankai, you must treat it with extreme caution. A Bankai is the ultimate manifestation of a Shinigami's soul.
If it is broken… it is permanently damaged and can never fully recover."
"Thank you, Sanada-senpai. I understand."
Raizen Kō bowed respectfully.
As a transmigrator, he already knew these facts, but he still appreciated the old man's sincerity.
Sanada Yūsuke had heard many rumors about Raizen Kō's achievements and believed he had the potential to one day become a Captain. That was precisely why he had taken the time to explain so patiently.
If it were any ordinary Squad Member choosing a sword, the old man likely would not have spared them more than a dismissive glance.
After all, Raizen Kō's feat of singlehandedly slaying a Menos Grande during the Soul Burial assessment and saving all the trainees and examiners had already spread throughout Seireitei.
Some even referred to him and Ichimaru Gin as the new "Twin Geniuses" of the Gotei 13, boldly claiming that Raizen Kō would inevitably rise to the rank of Captain in the future.
"Tch, old man Sanada," Ikkaku suddenly complained. "You sure weren't this polite when I picked my sword back then!"
"Hmph!" Sanada Yūsuke snorted. "That's because I never believed a brute like you would ever master Bankai. And even if you did, you certainly wouldn't take proper care of it!"
He then turned his sharp gaze toward Ayasegawa Yumichika.
"And you deliberately mispronouncing your Zanpakuto's true name. Utterly disgraceful!"
"The two of you are no better than that foolish Captain of yours, who only knows how to swing his blade wildly and can't even hear the voice of his own Zanpakuto!"
With that, Sanada Yūsuke flicked his sleeve and walked away without another word.
Left behind were a fuming Madarame Ikkaku and Ayasegawa Yumichika.
"Hey! Old geezer! Don't run away!"
"Come back and fight us if you have the guts!"
"I'll kill you!"
Raizen Kō, black lines practically forming on his face, quickly grabbed the two enraged Shinigami before they could chase after the old man.
Watching Sanada Yūsuke's retreating back, Raizen Kō narrowed his eyes slightly.
"…That old man is not simple at all."