In the original story, Gaara managed to rebuild his relationship with Shukaku. However, once Shukaku was extracted and Gaara experienced death before being revived, he was no longer a Jinchūriki by the end of the Fourth Ninja War.
In other words, Gaara in the original timeline never truly mastered Shukaku's power.
There are only two methods to control a tailed beast.
The first, as with Killer Bee and Naruto, is to reach mutual understanding — a bond of trust where the beast no longer seeks to disrupt the host, instead cooperating in battle while remaining within the seal.
The second, as with Uchiha Madara, is pure domination — using ocular powers to forcibly enslave the tailed beast and bend it into nothing more than a weapon.
Kenya's method was not as refined, but it was far safer.
Through the power of the Shinigami, even without relying on his Sharingan, he could freely enter the "seal space" where a Jinchūriki communicates with their beast. There, he could impose overwhelming pressure on Shukaku, ensuring Gaara could attempt communication without fear of rebellion.
As long as Kenya was present, Shukaku would never be allowed to rampage unchecked.
It was similar to Naruto's training with Kurama — except with an Uchiha Madara-like figure looming over his shoulder. The moment the Nine Tails dared to stir, Madara's eyes would suppress it back into submission.
Of course, Kenya did not claim to be on Madara's level.
But against the One-Tail, the weakest of the nine beasts, his strength was more than enough.
Every time Gaara trained, Kenya would also close his eyes, taking on Aizen's form, and enter the system's training ground to refine his own abilities.
The moment Shukaku stirred with violent intent, he would appear — and quell the rampaging tanuki.
Within twenty days, Shukaku erupted three times.
The first time, the villagers of Sunagakure nearly fainted in terror when the beast emerged near the training grounds beyond the village.
Rasa suppressed the sand with his golden particles, while Aizen stepped in to fully subdue Shukaku.
The villagers once again believed Rasa was still alive, and Aizen's reputation soared higher.
The next two incidents happened outside the village. Aizen alone suppressed Shukaku, with only Temari and Kankurō as witnesses.
When they saw him hold back the beast by himself, their astonishment deepened.
"Unbelievable… Lord Aizen, you're amazing!" Temari cried, her eyes shining with admiration as Shukaku's massive body deflated like a punctured balloon, retreating back into Gaara.
Whoosh!
At that moment, an Anbu wearing a ghost mask appeared with the Body Flicker Technique, kneeling before Aizen.
"Master Aizen, urgent summons. The Kazekage has called all Jōnin to assemble."
Aizen handed the unconscious Gaara to Kankurō and Temari, then gestured calmly.
"I understand."
The Anbu vanished as swiftly as he came.
"I've helped him reach the first stage of partial transformation, but a full beast form is still far off. Let him rest for now. It looks like I'll be occupied elsewhere."
He spoke gently to the siblings.
"The teacher's been focusing on Gaara lately, but I'm still your disciple too, aren't I?" Temari pouted, her voice carrying more warmth than complaint.
"Forgive me, Temari. Once this mission is done, I'll train you personally."
He reached out, ruffling her spiky "durian head" with surprising tenderness.
"Mm~" Temari's cheeks flushed pink, her expression soft like a cat basking in affection.
"Well then, return to the village quickly."
Aizen's form blurred and vanished.
Kankurō watched his sister still lost in the afterglow and muttered, "You know he's gone already, right?"
Temari's face flared red. She shot him a glare. "Shut up! Mind your own business!"
Grumbling, Kankurō fell silent as they hurried back with Gaara in their arms.
…
Inside the Kazekage's office.
Pakura, Baki, and several other Sand Jōnin had already gathered. As always, the Fourth Kazekage, Rasa, sat behind a thin veil of silk.
Boom—
The door opened as Aizen strode in.
"Lord Kazekage."
He nodded slightly at Rasa before taking his place among the assembled Jōnin.
"Mm."
From behind the veil, Rasa gave a slight nod before speaking:
"According to Anbu's investigation, there has been unrest in the Land of Water."
Of course, that was only from the others' perspective. From Aizen's eyes, it was his own Shadow Clone that was speaking.
Rasa continued: "Preliminary reports indicate the shinobi of Kirigakure have grown restless under Yagura's 'Blood Mist' rule. They've begun resisting. Tell me — do you believe there is profit for Sunagakure in this turmoil?"
Pakura considered for a moment before replying, "Lord Kazekage, if this news is accurate, recklessly intervening in another village's internal strife may yield no benefit — and could instead invite disaster. I recommend dispatching a small squad to investigate first."
At her words, Aizen's gaze shifted slightly.
Pakura… wasn't she the one who died during a mission to the Hidden Mist in the original timeline?
If so, then this mission… could it be that one?