Mayuri Kurotsuchi was eager and driven.
Although there wasn't much to be explored about the 'Summoning Jutsu,' and it wasn't particularly challenging, as a 'research project,' its value was not very high.
Yet, from it, one could glimpse the tip of a vast, unfamiliar knowledge iceberg.
No 'scientist' can resist the allure of knowledge.
"I have a problem," Naruto thought for a moment, taking his hand off a book, "Wait here for a moment."
He stood up and left. It wasn't long before he returned with a rabbit in his hand.
Mayuri squinted his eyes.
Although the Soul Society was the world of the 'dead,' it had a proper ecosystem, naturally with animals.
But, what sort of research project could a rabbit possibly be?
His studies had always started with 'souls.'
"I've placed a seal on this rabbit," Naruto said, setting the rabbit on the table, "It contains stored energy."
"I want Captain Mayuri to undo the seal and extract the energy without harming the rabbit."
Naruto had just gone out to temporarily make this rabbit akin to a 'Jinchuriki.'
"The life of a mere rabbit," Mayuri clicked his tongue, "Captain Uzumaki is truly merciful."
"However,"
"Does this seal have something to do with you?"
Naruto replied softly, "Captain Urahara wouldn't ask such irrelevant questions."
Mayuri clicked his tongue even louder.
"Oh, by the way, a little reminder," Naruto tilted his head and looked at him, "I'm not hopeful about your success in breaking the seal."
"After all,"
"This is something even Captain Urahara couldn't achieve."
Suddenly, Mayuri's demeanor became sharp, his voice harsh, "Captain Uzumaki has quite the faith in that man."
"If he were capable, he wouldn't have fled the Soul Society like a rat."
"His failure doesn't imply mine."
He lifted the rabbit by its ears. "Just wait, Captain Uzumaki. Next time, what I want won't be just this little bit."
"If you fail, feel free to come back for a new rabbit anytime," Naruto cheerfully offered him in greeting.
Mayuri Kurotsuchi left with an imposing air.
Watching his retreating figure, Naruto contemplated.
Kisuke Urahara hadn't delved deeply into breaking the "Four Symbols Seal." It was merely a casual mention.
However, as expected, by exploiting people's "competitive spirit," one can indeed motivate a lot of effort.
Picking up a book, he began to read.
Only on the first page, Naruto was already struck by the accuracy of Urahara's past assessment: Mayuri really was a clever and capable individual.
He modified the "Summoning Technique," casting it through Kido, making it about as challenging as the mid-ranked "Binding Kido," somewhere in the twenties or thirties.
He further simplified the "technique," making it even more minimalist than before.
And subsequently, in the next book, he deduced the "Reverse Summoning Technique," combining it with the "Shunpo" technique to develop a way to utilize the "Summoning Technique" for "rapid spatial transfer" within the same space. Yet, given it's only been a year, this technology is not yet fully perfected.
Mayuri candidly acknowledged the technique's flaws in his book. Although it's spatial transfer, the initiation time is too long, diminishing its significance.
Moreover, it requires extremely delicate control over spiritual power and a strong reaction capability. Throughout Mayuri's writings, it's clear he's not particularly eager to harness this power, as further research would consume enormous time, hence he stopped there. However, he also noted that if Naruto were interested, he could continue the research if Naruto could offer him something he wanted.
Truly a man acknowledged by Kisuke Urahara.
These books benefited Naruto greatly.
The prolonged lifespan of a Shinigami results in a life relatively unchanged.
Naruto's life revolved around managing internal team affairs and then repeatedly researching the "Four Symbols Seal" and "Reaper Death Seal."
Occasionally, Kurama would complain, blaming Minato for sealing his other half away, leaving him unable to train "Bankai."
Or Mayuri would come, with a grim face, reaching out to demand a new rabbit.
Breaking the "Four Symbols Seal" is a daunting task.
The duty of a sealer is simply to seal. For those who break seals, there's much to consider.
Without realizing it, the days of cherry blossoms blooming have arrived once more.
Sosuke Aizen came looking for him.
After exchanging greetings.
"Naruto-kun, you don't seem to have anything urgent going on lately, right?" Aizen asked.
Naruto shook his head.
"Would you like to attend the entrance ceremony of the Shin'ō Academy?" Aizen extended an invitation.
Naruto was taken aback, looking out the window: "So it's that time of year again."
"But why would you suddenly think to invite me, Sosuke?"
Aizen smiled, "Naruto-kun, you know me. I attend the entrance ceremony every year."
"Every year, I hear the students talking about wanting to meet Naruto Uzumaki, the youngest captain."
"They're so eager."
"I wanted to fulfill their wish, so I came to invite you."
Naruto nodded.
The emotions reflected back by his Kagura's Mind Eye showed that this statement was very sincere.
"Since Sosuke put it that way, I have no reason to refuse," Naruto agreed.
Aizen lifted his head, also gazing out the window, where a cherry tree stood in the courtyard of the Seventh Division, its petals cascading like rain with the breeze: "That's wonderful, Naruto-kun."
"If only the Soul Society could always be this way."
Naruto was momentarily stunned.
His Kagura's Mind Eye fed back that this statement was a 'lie.'
The day of the entrance ceremony arrived swiftly.
Having two captains present brought joy to Principal Houga.
Naruto was already accustomed to such grand occasions and recited the speech he had prepared the night before.
After he spoke, Sosuke Aizen took the stage immediately afterwards.
His speech content was different from the last time; it seemed he crafted a new speech for each new class every year.
At the end.
Aizen smiled at them, "I hope you all become exceptional Soul Reapers."
"In previous years, I've always demonstrated the release of my zanpakutō to the new students as a blessing."
"But this year, Captain Uzumaki is also here."
He turned his head, looking at the blonde figure in the audience, "Naruto, would you like to demonstrate the release for them?"
Naruto shook his head, as his sword wasn't suitable for display.
Aizen raised his hand, placing it on his sword, "Then it'll be me, as usual."
He drew his sword, chanting the release.
"Shatter, Kyōka Suigetsu."
A reflection of flowing illusions was born, casting false images. The students gasped in amazement.
Naruto's gaze pierced through the illusory shadows before him, smiling as he fixed his eyes on Aizen standing at the podium. He was no longer affected by this level of "illusion."
"Every person's zanpakutō has different abilities," Aizen said softly, "This is mine."
After a moment, he sheathed his sword. ☜ Wo Academy's Dean scratched his head. Something seemed to be missing this year.
After seeing off the two captains and agreeing with Naruto that they'd meet at the izakaya when time allowed, it suddenly dawned on him. During the final release of his zanpakutō, Captain Aizen hadn't said the usual things.
In previous years, when he demonstrated his zanpakutō to the new students, he always introduced the specific abilities of his "water-type" zanpakutō, which, while not powerful, was one of the few in the Soul Society with an "illusion" ability. But this year, there was no introduction. Was it forgotten? Or perhaps because the speeches by the two captains went long, he omitted this part.
Naruto returned to the barracks.
The lie that slipped out of Sōsuke Aizen's mouth that day was something he took note of. But... it seemed like that was the only "lie."
Whether it was during his speeches to the Shin'ō Academy students or his everyday interactions, Sōsuke Aizen remained the same sincere and gentle Captain Aizen.
Kaname Tōsen had always remained a subject of interest for him.
Despite his unchanged demeanor of keeping to himself and refusing to interact with fellow practitioners, disappearing right after training sessions ended, Naruto managed to gather information about Kaname Tōsen's "Shikai" from the Ninth Division members.
It was a zanpakutō named "Suzumushi," which possessed the ability to hypnotize.
"Hypnosis"—this was a power that piqued his interest.
However, even though he had learned about its effects, he still couldn't ascertain how exactly Tōsen's blade functioned.
Was it by merely seeing with one's eyes that caused the hypnosis?
Or was there another method?
As Naruto maintained his vigilance towards them, he continued with his own research.
He had deciphered the outcome of "Reaper Death Seal".
It was similar to the conclusions deduced from the scroll Orochimaru had given him.
Indeed, it was a technique akin to a "Summoning Technique".
Benefiting from Orochimaru's findings and the complete "Reaper Death Seal" technique, he had also reverse-engineered a method to unlock the seal.
It required finding the "occult object" of that wicked spirit and using it to cast the technique, summon the Death God, and when it appears, cut open its stomach to release those souls, allowing them to find their rightful places.
Fragments of souls would return to their bodies.
The departed souls would head back to the Pure Land.
While he progressed smoothly, Mayuri Kurotsuchi faced some hurdles.
The challenge of safely releasing the power within the "Jinchuriki"'s body troubled him deeply.
Despite significant progress over time, evolving from being unable to guarantee the rabbit's life to now being able to keep the rabbit alive for up to a week after releasing its power, both Naruto and Mayuri find the result of significantly shortened lifespan unacceptable.
Another year passed.
Naruto was handling affairs within the barracks when the Vice-Captain, Kotsuba Jinryūemon, hurriedly entered, "Captain, we have an intruder who has forcefully defeated the gatekeepers of 'Seireitei' and is advancing with apparent hostility, having defeated several seated officers without causing any fatalities yet."
"An intruder?" Naruto rose to his feet.
"He is a man with long black hair and a little girl with pink hair on his shoulder," reported Kotsuba Jinryūemon. "He possesses considerable strength."
"We couldn't gather any more information."
"We couldn't even force him to reveal his Shikai."