The reason Ōetsu Nimaiya accepted Gosuke Shigure's explanation so easily—accepted even the impossible claim of reincarnation—came from one thing alone:
He felt it through the blade.
And beyond that, he understood the sword Shigure carried better than anyone else alive.
The Zanpakutō now half-dead in Shigure's hands had once belonged to Tsunayashiro Shusui, Shigure's previous incarnation.
It was a singular blade—exceptional even among all the miracles Nimaiya had ever forged.
If Ryūjin Jakka was the oldest and most powerful fire-type Zanpakutō…
If the future Hyōrinmaru would become the pinnacle of ice…
Then Shusui's Zanpakutō had been the most potent soul-type Zanpakutō ever produced.
Even Nimaiya, its creator, had never fully understood how a blade like that came to be.
Years ago, when that Zanpakutō first awakened, Ōetsu had immediately taken interest in the Shinigami who wielded it.
In its sealed form, Shusui's blade looked ordinary—nothing unusual at all.
But Tsunayashiro Shusui possessed an absurdly rare talent.
He had taken a normal asauchi and evolved it far beyond its intended shape—turning it into a weapon that manipulated the deepest aspects of the soul, a category even Shinigami rarely touched.
Given time, Tsunayashiro Shusui would have surpassed even Genryūsai Shigekuni Yamamoto, wielder of the strongest heat-type Zanpakutō.
And indeed, Shusui had grown into one of the most formidable powers of his era.
During that period, the Tsunayashiro Clan maintained extremely close ties with the Soul King Palace.
Because of that, Nimaiya approached Shusui personally, and the two formed a genuine friendship.
When Ōetsu later learned of Shusui's death, a rare heaviness had washed over him.
For all his potential, Shusui had not reached his absolute peak.
His soul-type Zanpakutō had never fully displayed its ultimate brilliance.
Ōetsu had wondered ever since whether such a blade could ever appear again.
As the creator of all Zanpakutō, he cared deeply about the fate of the blades themselves.
The deaths of Shinigami, by contrast, hardly fazed him—after all, he had witnessed countless deaths since the inception of Soul Society.
But he never expected that, one day, the sword he believed lost forever would appear before him again.
The soul-type Zanpakutō still existed.
Not only that—
It had brought its original wielder back into the world.
Tsunayashiro Shusui had been reborn.
Reborn as Gosuke Shigure.
"Figures," Ōetsu murmured. "A soul-type Zanpakutō would pull off something like that."
He exhaled and turned his eyes back to Shigure.
"So when this blade resurrected you, your soul changed so much that you can't supply it with spiritual power anymore—is that right?"
"That's right," Shigure answered.
Ōetsu rubbed his chin.
"This is a first even for me. Soul-type Zanpakutō are already insanely rare, but resurrection? That's unheard of."
"Sure, strong Shinigami don't just dissolve after death—they're sent to Hell. But from ancient times til now, there isn't a single case of someone escaping Hell and returning to life."
Shigure smiled faintly.
"But if anyone can solve this, it's you. First time or not."
Now that he had revealed his identity, he spoke to Nimaiya with the ease of Tsunayashiro Shusui rather than Gosuke Shigure.
Ōetsu snapped his fingers.
"Damn right! When it comes to Zanpakutō, nothing is impossible for me!"
He held out a hand.
"Lemme see your current blade too."
Shigure handed over the other Zanpakutō.
Ōetsu ran his fingers over it, sensing its nature.
"This one's way more lively. Strong vitality, powerful resonance… yeah, this blade's loaded. Shusui-kun, I swear, you're ridiculous."
"You actually managed to end up with two insanely powerful Zanpakutō in two different lives. First time I've seen a Shinigami pull that off."
Shigure chuckled.
"If we're counting numbers, no one matches you."
Œtsu waved a hand.
"True, I've forged tons of them, but they're all sealed-state bases. What you've got here is awakened, evolved power. Whole different category."
As he spoke, an idea sparked in his mind.
"I think I know how to fix your other Zanpakutō."
"Oh? Go on."
Ōetsu folded his arms.
"We take your old Zanpakutō and your current one… and fuse them."
"Reforge them into a single blade.
Your current Zanpakutō will act as the carrier—housing two spirits at the same time."
Shigure frowned.
"Can that even work?"
"It should," Ōetsu answered confidently. "I've never done it before, but in theory? Totally possible."
"Then let's do it."
He was decisive as always.
After Urahara Kisuke failed to solve his Zanpakutō dilemma, Shigure had set his hopes entirely on Ōetsu.
Now that he had finally reached the Soul King Palace, he would attempt anything Nimaiya proposed.
Because if even Ōetsu Nimaiya, the Blade God, could not resolve this problem—
then no one in existence could.
And so, Ōetsu began the forging process.
The first step was to dismantle Shigure's old Zanpakutō—the soul-type blade.
Shusui had died, and the reborn Shigure's altered soul could no longer sustain the sword.
The only way forward was destruction and rebirth: shatter the old blade, extract its spirit, and merge it into a sealed-state base that resonated with Shigure's current soul.
But because Shigure already possessed a new Zanpakutō, Ōetsu chose an unprecedented path:
A single sealed form that would carry two Zanpakutō spirits.
A miracle no Zanpakutō creator had ever attempted.