Given Tōsen Kaname's starkly different outward behavior and inner thoughts, combined with Ichimaru Gin's clever disguise, the death of the Fifth Division's Third Seat, and the questions Kyōraku Shunsui had raised, Yoriichi had already asked Kyōraku Shunsui to investigate Tōsen Kaname much earlier.
As the Captain of the Eighth Division, he should be adept at acquiring information.
Within the Seireitei, the only Shinigami Yoriichi currently trusted implicitly were Yamamoto Genryusai and his two senior brothers.
Now, when Kyōraku Shunsui brought up the results of his investigation into Tōsen Kaname, Yoriichi immediately focused his mind:
"What did you find?"
He hoped he had guessed wrong.
Because if Tōsen Kaname had problems, then it would be difficult to say whether Hirako Shinji was innocent.
He couldn't possibly have been oblivious to the affairs of his subordinates during his nearly one hundred years as Captain, could he?
That would be too irresponsible.
Kyōraku Shunsui looked around, and only after confirming there were no outsiders nearby did he slowly reveal what he had discovered:
"Before Tōsen Kaname became a Shinigami, he had a close friend in Rukongai named Kaede."
"Kaede married into the Tsunayashiro family ninety years ago."
"Eighty-seven years ago, she died, murdered by her husband."
"Within two years after that, an incident occurred in the Official Quarter where a Rukongai resident accused a noble."
"Although this incident was suppressed at the time, some records still exist."
"Upon investigation, the Rukongai resident who accused the noble at that time was Tōsen Kaname."
"His close friend was killed, and he was unable to accuse anyone."
"Yoriichi, what do you think Tōsen Kaname's view of nobles and Shinigami was at that time?"
Yoriichi slightly furrowed his brows: "Resentment?"
"Correct." Kyōraku Shunsui first smiled faintly, but soon, his expression returned to seriousness,
"However, this is also the strangest part."
"In the decades after that, Tōsen Kaname enrolled, graduated, and became a Shinigami, never showing even a hint of such emotions again."
"Although he claimed that becoming a Shinigami was to change all injustices, he never took any action."
"He became a high-ranking Seat Officer within ten years while serving by Vice-Captain Aizen's side."
"Adding to that the things Matsumoto Rangiku encountered..."
"If, before, my estimated probability of a potential rebel in the Fifth Division was 30%, it is now 70%."
"I subtly asked Captain Hirako, and he himself was completely unaware of this."
"Therefore, Yoriichi, I think you can act now."
"Seal off all information and first detain Tōsen Kaname."
"Whether he participated in rebellious acts or not, these influences must be isolated to prevent harm to the Seireitei."
"..."
Yoriichi fell silent, the sudden suggestion to act leaving him somewhat troubled.
Although he had been mentally prepared, when he actually heard the suggestion, he couldn't help but feel conflicted.
After all, the rebellious act had not yet been confirmed; the previous suspicions were merely suspicions.
Once action was taken, the nature of the situation would be entirely different.
Seeing Yoriichi's expression, Kyōraku Shunsui also felt quite helpless.
"I know what you're worried about, but now is not the time to judge whether Tōsen Kaname has a hidden reason."
"Once the Fifth Division's rebellious acts are confirmed, it will be too late to act then."
"It's just detention, cutting off the transmission of information."
"No matter who the mastermind is within the Fifth Division, they won't be able to know about our actions and deductions."
"If you can't bring yourself to do it, then let me."
"Even if he truly has a hidden reason, he won't blame you after his innocence is cleared."
"This is also my duty as your senior brother."
Kyōraku Shunsui slowly stood up, his usual carefree expression vanishing without a trace.
His tolerance did not extend to those Shinigami who harbored strange ideas about the Seireitei.
Although he usually appeared lazy, he knew deeply that rebellion would lead to the deaths of innocent people and trigger countless tragedies.
"..."
After a moment of silence, Yoriichi's voice slowly rang out: "Forget it, Senior Brother, I'll do it."
"He is a member of my Ninth Division; even if there's a problem, it should be handled by my Ninth Division."
Although Yoriichi was unwilling to believe that Tōsen Kaname would betray the Seireitei and the Shinigami, the various anomalies in the Fifth Division were clearly laid out before him.
All that was missing was obtaining evidence and knowing their objective, and everything would be revealed.
Unfortunately, obtaining evidence was the most difficult part.
Mere suspicion was far from enough; even if he could perceive Tōsen Kaname's abnormality with Touhou Sekigan, it was still just his own personal observation.
If he were to use that as evidence, no one would accept it.
So he could only approach it indirectly.
Kyōraku Shunsui glanced at Yoriichi, then let out a long breath and added:
"If you are going to detain him, it's best to choose a time when he is out on a mission."
"Only then will his disappearance not attract attention."
"I will also keep a close eye on Ichimaru Gin and Aizen. I hope we can achieve a swift victory; the Seireitei cannot suffer any more losses."
Yoriichi nodded, tacitly agreeing with Kyōraku Shunsui's words.
Not long after, with a 'splash,' Kuchiki Sōjun emerged from behind a curtain, his face flushed.
At a glance, his mental state was incredibly vibrant, and his physique had become lighter.
Under the judgment of Touhou Sekigan, all his internal injuries and ailments had disappeared.
If nothing unexpected happened, with his current body, he could live for another thousand years.
On the other side, Kuchiki Kouki, Kuchiki Sōjun's sister, was also gradually recovering.
Aside from her heart condition, her physical health had surpassed that of most newborn Shinigami.
Because the Red blood and white bone hell could even completely wash away physical fatigue, her heart condition had also significantly lessened at this moment.
She felt lighter than ever before, as if she were stepping on clouds.
Perhaps, in this state, she might find some peace and completely bid farewell to the past...
Who can truly say anything about a heart ailment?
...
After leaving the Gotei 13, Tsugikuni Yoriichi followed Kyōraku Shunsui to the Great Spirit Book Corridor.
There, they roughly learned the time Mimihagi appeared and its general origin.
A million years ago.
This timeframe was quite subtle.
Although a million years ago, Mimihagi was not called Mimihagi; at that time, it was just an unknown entity, revered by the Rukongai residents.
But.
That was the time the Soul Society was born.
It commanded the power of stillness.
No means were effective.
Thus.
Kyōraku Shunsui, synthesizing the known information, made a bold guess.
Could it be the power of the Soul King?
Because only this could explain it.
The Red blood and white bone hell, as the strongest medical treatment, couldn't even cure a mere lung disease.
He told this deduction to Tsugikuni Yoriichi, who looked thoughtful upon hearing it.
The Soul King, he had heard of him.
But because the time was too distant, it had become a legend...
If Mimihagi was truly related to the Soul King...
A flash of inspiration struck Yoriichi's mind:
"Senior Brother, do you think there's another possibility, that not only Mimihagi, but other places also contain the Soul King's power?"