Tsunade's knowledge of the Mangekyou Sharingan could be neatly summarized on the back of a very small napkin. Historical texts and dusty scrolls were, in her professional medical opinion, a fantastic cure for insomnia.
She'd always believed that if a problem couldn't be punched, healed, or bet on, it was probably a problem not worth having.
But this… this was interesting. Hearing Azula mentioning the side effect of permanent blindness made her medic-nin instincts sit up straight.
And the fact that only one Madara Uchiha, had ever achieved the "Eternal" upgrade in the Uchiha history make it even more a problem worth conquering.
Her friend, with a heart full of fire and with monstrous talent, was precisely the type of person to awaken such a cursed power.
"Right," Tsunade muttered, more to herself than to Azula. "So, let me get this straight. After acquiring god-like ocular powers, the cost of using them is your actual eyesight?"
Azula, the picture of eerie calm, merely shook her head. "The time for that discussion hasn't come. It's tied to the secret I'm prepared to share with you. So, don't dawdle. My patience, unlike my chakra, is not a boundless resource."
A faint, knowing smile played on her lips, and she let the subject drop like a stone, her eyes scanning their surroundings with casual intensity. They were, after all, standing in the middle of a Konoha street.
Even with her confidence that no one could eavesdrop on her without losing their eardrums, it paid to be paranoid. After all, in a village of professional spies, the walls had not only ears, but sometimes also roots and shadow clones.
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While Tsunade was contemplating a future as an ophthalmologist, and Azula was leading their tour of Konoha's finest architecture (which mostly consisted of evaluating the structural integrity of various buildings should one need to, hypothetically, collapse them), other, equally chaotic plots were underway.
In one corner of the village, Nawaki and a profoundly unamused Fugaku Uchiha were engaged in a silent, intense "competition" that mostly involved Fugaku trying to meditate and Nawaki attempting to balance a kunai on his nose.
Meanwhile, Mito Uzumaki who had successfully set the Third Hokage on fire was also busy.
Deep within her own consciousness, in a space that looked suspiciously like a very cozy, chakra-infused tearoom, Mito sat across from her lifelong tenant and verbal sparring partner: the Nine-Tailed Fox, Kurama.
"So," Mito began, pouring a metaphysical cup of tea. "What do you think of my idea?"
Kurama let out a snort that could vaporize a small lake. "Hmph! You and your 'ideas'. You're talking about fiddling with the very fabric of souls? Woman, a slight mishap wouldn't just be a 'simple seal matter.' It would create a catastrophe that would make war nothing but simple humans problems.
Mito sipped her tea, entirely unfazed. Sometimes, she wondered if Kurama and the legendary Uchiha ancestor, Indra, hadn't been separated at birth.
He had the same 'Tsundere' personality as every Uchiha she knows.
"I understand the risks, old friend," she said softly. "But you know this isn't a matter of want. It's a matter of must. Azula's Otsutsuki… they aren't just another clan to be negotiated with."
"Even if Hashirama and Madara were at the peak of their power, standing side-by-side, I fear they would be little more than a bump like Azula said. And that's not even the most terrifying part. What if the Otsutsuki are just one clan among many in the cosmos? What if the things lurking out there in the void make them look… tame?"
Azula had, perhaps unintentionally, turned Mito's healthy caution into a thriving garden of paranoia.
Seeing the girl—whom she'd come to see as a granddaughter—push herself to the brink every single day, all for the slim chance of saving a world that didn't even know it was doomed… how could Mito not be moved?
From her perspective, the entire fate of the Ninja World was resting on the shoulders of one brilliant, terrifyingly determined young woman.
With her knowledge of the future and her prodigious Yin release talent, Azula was poised to surpass everyone Mito had ever known, Hashirama included.
And for that, Mito was determined to help. Tsunade's 'Forbidden Art: Scarlet Beast Seal' was one such project. Or, to be more accurate, it was the clumsy, first-draft, "we-sure-hope-this-doesn't-explode" version of the real technique.
The concept, in its simplest form, was straightforward: a chakra battery.
A storage seal for Tailed Beast energy.
But its origin was pure, unadulterated Azula-logic. One day, after reviewing some scrolls, the girl had mused aloud: "Tailed Beasts recover their chakra at an absurd rate. Kurama, for instance, could likely regenerate half his total power in a single day."
She'd then paused, that familiar, dangerous spark of genius in her eyes. "So, theoretically, if one designed a seal that siphoned off just 1% of his daily regenerated chakra… in about a hundred days, you'd have accumulated a separate reservoir of chakra equivalent to the Fox himself."
The idea was born from a future fact Azula remembered—of Kurama being split into Yin and Yang halves—but this was a gentler, more persistent approach.
Gentler, of course, being a relative term when discussing siphoning the energy of a primordial demon.
The reason it remained hopelessly incomplete was a laundry list of terrifying "what-ifs." First, there was the corrosive nature of Tailed Beast chakra.
Without the beast's passive cooperation, it would erode the user's mind and body. The best-case scenario was the user becoming a mindless, rampaging beast with phenomenal regeneration.
The normal scenario was being dissolved from the inside out into a puddle of angry chakra.
Then there was Problem Number Two. If you amass such a vast, concentrated volume of primal energy, what's to stop it from developing its own will?
The last thing anyone needed was to painstakingly create a new Divine Tree, only for it to develop a personality and decide it really, really didn't like its creators.
There had been some progress, of course. Tsunade's prototype seal was stabilized by a blend of Azula's and Mito's own chakra.
Having hosted Kurama for decades, Mito's chakra had undergone certain… mutations, making its essence closer to the fox's, a little more resilient to the corrosive effect.
But even with that advantage, the results were harrowing. When Tsunade released the seal's first-stage limiters, she had to fight tooth and nail not to lose herself to the raw power, and it only contained a diluted fraction of their combined energies.
The thought of what would happen if it were filled with the genuine, unfiltered chakra of one—or heaven forbid, multiple—Tailed Beasts was enough to make even a legend like Mito break out in a cold sweat.
But it wasn't her true focus, the subject that commanded every ounce of her formidable intellect and will, was far more profound. It was the soul—the immutable essence of a being, and the fragile, flickering flame of her own life force.
The cruel, unadorned truth was that her lifespan was nearing its end. The sands in her hourglass were running perilously low.
If she lived a life of quiet meditation, of preserving her strength and forswearing the use of chakra, she might yet stretch her remaining time to a decade.
A decade.
It sounded like a substantial span to some, but to Mito, who had watched almost a century unfold, it was the blink of an eye.
And such a passive existence was a fantasy; she was Uzumaki Mito, and her heart would not allow her to stand idly by. Not with the gathering storm clouds threatening her clan, a tempest she fully intended to meet head-on.
Her mind, ever sharp and calculating, had already run the numbers. Factoring in the immense chakra cost of the intervention she was planning for the Uzumaki, her realistic timeline shrank dramatically. Five years.
She had five years left to burn, five years to make a difference that would resonate for generations.
A grimace touched her serene features. Five years was simply, unequivocally, insufficient. How could she possibly hope to use that sliver of time to help her beloved disciple, Azula, bridge a chasm of power and knowledge?
The gap between the girl and the ancient, thousands-year-old clan she would one day confront was not a simple ditch to be leaped over; it was a yawning canyon, carved by millennia of tradition, bloodline limits, and accumulated might.
And so, from this crucible of desperation and unwavering devotion, a final, audacious plan was forged. It was simple in its objective, yet staggering in its cost. She would give Azula everything.
Not just her teachings, but her very essence. She envisioned a legacy transfer, a concept that resonated strangely with something Azula herself had once described as the Ōtsutsuki's Kāma.
A living seal, a compressed archive of a lifetime's worth of power, knowledge, and genetic potential.
If she could succeed—if she could imprint the very core of her being, the unique blueprint of her Uzumaki vitality and the vast library of her mind, directly onto Azula's soul—then her physical departure would become irrelevant.
Her guidance would not end with her last breath.