Ryusei let the silence stretch a few seconds more before he allowed himself something rare, an open smirk.
His slit eyes narrowed with the faintest glint of play.
"But if you really care so much," he said at last, voice light but edged, "then there is something you can do. This window won't last forever. If I'm to stand against what's coming, then I need to be made as strong as humanly possible, as quickly as possible. That's something only you can help with."
Tsunade blinked, caught off guard. For a heartbeat, her chest tightened again, but not from dread this time.
Slowly, her lips curved, her posture loosening, the heavy aura that had clung to her earlier fading as she slipped back into her usual rhythm.
"So that's what this is," she said with a soft scoff, shaking her head slightly. "The brat who won't admit he needs anyone finally asks for my help. You wear that proud face all day long, yet here you are, sounding almost spoiled."
Her eyes glinted, sharp but warmer than before. "You're lucky I don't let that go to your head."
Strangely, she felt a small flicker of happiness.
The boy who had carried himself so cold and distant, who had thrown accusations and truths at her like knives, was now admitting, however reluctantly, that he needed her.
That acknowledgement touched something in her, even if she'd never admit it out loud.
Ryusei, meanwhile, hid his satisfaction perfectly. Internally, he marked it down as another step forward, another thread binding her to him.
'Good. Let her tease. Let her enjoy this little shift. If she thinks she's gaining something from me, she'll only chain herself deeper without realizing it. After all, how many shinobi have begged to be her students, only to be brushed aside with cold indifference? Yet here she is, proud and almost glowing, just because I asked.'
Outwardly, he scoffed faintly, tilting his head just enough to look dismissive.
"Tch. Don't get carried away. I said you could be useful, not that I'll cling to your skirt like some Academy dropout."
Her brow arched, amused by the sharp edge in his voice that failed to mask the truth behind his words. "Hmph. Keep talking like that, brat. You'll be begging me before long."
Ryusei gave her a side glance, his mouth quirking upward in what almost passed for a grin. "If I ever beg, it won't be you I'm begging to."
The banter sparked, light but loaded, their tones brushing sharp edges against each other like flint and steel.
Yet under it, both of them knew, something had shifted.
She teased him sharply. He played tsundere.
And in between, their distance closed another notch.
Their banter soon drifted directly toward her abilities, Tsunade slipping into her usual bragging without much effort.
Every time he prodded her with a half-reluctant "question," she puffed up proudly, almost glowing at the chance to explain, as though he were forcing her hand to lecture him.
Ryusei let her talk, giving just enough feigned admiration to keep her going, while inside his thoughts ran sharp.
He realized something important.
Her overwhelming fighting power wasn't just brute force or raw talent.
The cornerstone was her medical expertise.
Thanks to her deep understanding of human anatomy and medical chakra control, she had mastered the most basic concept called the "chakra enhancement" beyond anyone else alive.
She could squeeze out strength, speed, reflexes, and durability far past the safe limits other shinobi could ever touch, because she knew exactly how much her body could handle without breaking, and even heal it with her other technique.
That was the real root of her level of monstrous taijutsu.
But it didn't stop there. That next pillar was her unique 'Creation Rebirth' technique.
A technique no one else in the world could replicate, born of her own genius in medical arts.
By preemptively spreading Yang Release across her entire body, she could instantly regenerate any wound, no matter how fatal, making her close-range combat overwhelming.
Attacking her was like striking at an immortal; your blows only opened a gap for her counter.
Yet Ryusei noted the flaw, the one even she couldn't ignore: it forced her cells to divide, shortening her natural lifespan every time it was used, since they had a limited number of times they could divide perfectly.
So, it was power at a cost, a technique not meant to be abused or used constantly.
This was why, in the original timeline, she had looked like a worn-out centenarian when her mask finally cracked during Pain's attack.
By that logic, she might even now already appear far older than her thirty-five years without that technique.
The only reason she still carried the face and figure of her prime was thanks to another top-secret medical jutsu, which allowed her to keep her perfect youth and form externally, the one she clearly guarded closely. Ryusei didn't dare ask about it directly, nor was he interested much.
After all, not that he minded. What stood before him was, to his eyes, the most enticing woman in the world.
Whatever technique she used to preserve herself, whatever the truth beneath the surface, it changed nothing.
Still, he speculated privately. Perhaps the only reason she could sustain such a jutsu and Creation Rebirth for so long without collapsing was her Uzumaki blood.
Their famed longevity likely gave her cells more room, more divisions to spend than any ordinary shinobi could dream of.
And then there was the final piece, the one that tied everything together: the Yin Seal.
A masterpiece of Uzumaki fuinjutsu and medical mastery.
Every day, the surplus of her vast Uzumaki-Senju reserves was siphoned off and sealed away, compounding over the years into an enormous stored pool.
He smirked slightly as she bragged about it, recalling how rare it truly was.
Hashirama, Tobirama, and even Hiruzen, the most likely other names that should have had it as well, hadn't been able to learn it.
It required not only chakra reserves but medical control of the highest order. Mito Uzumaki, her grandma, had been able to pass it to her, and only her.
When she released it, she gained an explosion of chakra, allowing her to fuel chakra-enhanced strength and Creation Rebirth at a terrifying level.
And her advanced form, Mitotic Regeneration, took it even further, healing wounds so rapidly she could recover from being impaled by something as absurd as a Susanoo blade in mere moments, automatically, without even her conscious thought, not to mention hand signs.
Together, the three techniques formed a perfect trinity: Yin Seal providing fuel, chakra enhancement unleashing it for offense and defense, and Creation Rebirth ensuring she could fight recklessly without consequence.
The more he thought about it, the clearer it became.
In his past life, he remembered the misconceptions that Tsunade was "weaker" than Jiraiya and Orochimaru.
But now, standing before her, hearing her explain while recalling what he knew of her feats, Ryusei felt certain.
The three of them had always been equals, with only minor shifts depending on time and circumstance.
He let his eyes linger on her as she smirked, puffing herself up with pride at his questions.
Outwardly, he gave her a reluctant nod, playing the role of the boy being lectured.
Inwardly, though, his grin was sharp. 'So this is the real foundation of the so-called Legendary Sannin. No wonder she could still match monsters decades later. And she's standing here now, bragging to me like I'm her only audience. Perfect.'
The talk shifted again, flowing from the overview of her abilities to Ryusei finally hinting at what he wanted.
"I want to learn them," he said, his voice calm but firm. "All three."
Tsunade blinked, then let out a sharp laugh.
Her lips curved into that smug, almost childish smirk, the kind she wore when she puffed herself up like an invincible senior.
"You?" she said, pointing a thumb toward herself with deliberate pride.
"You've got guts, brat. I'll give you that. But do you even understand what you're asking? These aren't fireballs or other flashy tricks. You need years of medical foundation before you can even scratch the surface."
Her finger then flicked up to her forehead, tapping the faint mark of her Yin Seal.
"And this? This seal isn't just medical ninjutsu. It's fifty percent fuinjutsu. Maintenance, application, storage, it's as much about writing the body as healing it. Without that foundation, you'd blow yourself up before you even managed a crack."
She tilted her head, eyes narrowing as she looked him over more carefully.
"You've got the build for taijutsu, I'll give you that. Strong body, clean movement, you don't stand like a rookie. But without advanced medical knowledge and chakra control? Forget Monster Strength. You'd only end up breaking your own arms trying to copy me."
Her mocking tone lingered in the air, smug and sharp.
Ryusei listened quietly. Inside, he was smirking. 'If that bum Sakura managed to pull it off in a few years, why wouldn't I?', he thought.
With his transmigrator's enhanced insight and spiritual clarity, and a Senju body tuned to Yang Release, he already knew he had the perfect toolkit.
So instead of talking back, he simply raised his hands.
One glowed with the pristine green chakra of the Mystical Palm, controlled and steady.
The other flickered with a darker orange light, the Yang Palm he had developed himself.
Both jutsu ran clean and smooth, without even a tremor of wasted chakra.
Tsunade froze, her smirk vanishing instantly.
Her eyes sharpened as she watched, narrowing in disbelief.
She stepped closer without realizing, scrutinizing every flicker of chakra, every movement of his hands.
The Mystical Palm was flawless, so refined that it was on par with the top healers in Konoha's hospital. And he was thirteen.
She hadn't expected it at all, that on top of all those offensive moves, he'd somehow found the time to refine medical ninjutsu to such a degree.
Perfect green healing chakra.
The standard could be applied in countless ways; some shinobi specialized it toward bone repair, others toward muscle restoration, or even internal damage.
But to see the baseline performed so flawlessly meant something else entirely.
It marked someone as superior across the board, regardless of which specialization path they later pursued.
Her lips tightened, a groan slipping out unbidden.
Every pointer she had just thrown at him, every mocking jab, came biting back at her.
And then the orange glow. Her heart gave a heavy thud.
She recognized it instantly for what it was, or rather, what it was trying to be, thanks to her mastery of the Yang Release.
Not true regeneration. It didn't heal old wounds, didn't restore what was gone.
But it was a proto-form. Like a crude, miniature cousin to her own Creation Rebirth.
It wasn't learned. It was obviously created, she instantly realised, thanks to her experience.
Her mind raced. 'At his age…? Such a custom technique? No one in Konoha has anything like this… not even Orochimaru could have pulled this out at thirteen. What the hell is this brat?'
She clenched her jaw, staring hard at him. Inside, she was staggered.
Her lips tightened. She hated to admit it, even to herself, but the conclusion was inescapable.
This brat wasn't just talented.
He was a hidden medical genius.
In fact, he might already be the most qualified person she had ever seen, behind herself alone, to truly master the pinnacle of medical arts.
Truly perfectly qualified to become her first full-time disciple, even without any previous affiliation.
But, outwardly, she groaned louder, trying to cover it all up, due to her typical petty mind.
"Tch. Fine. You qualify. Barely. You might have the footing to start on Monster Strength. Maybe even Creation Rebirth. But don't get too full of yourself. Those techniques aren't parlor tricks you can whip up in a few months. Years, brat. Years of discipline. And don't forget, your immaculate Senju blood's probably doing half the work for you anyway."
Her voice rose sharply, as if trying to reassert her authority, even as her brows twitched at the smug, narrow-eyed look plastered across his face.
She felt the urge to sock him in the arm just to wipe that look off.
For the first time in years, she actually wanted to playfully hit someone for teasing her like this again.
'Damn brat… doesn't he know how to show respect to his elders?'
And then she caught herself. Her hand lowered. She exhaled slowly.
Before she could chase the thought further, she remembered something.
Her lips curled back into a smirk.
"Don't get too cocky yet. Even if you've got the medical part, the Yin Seal, for example, still isn't something you can muscle through. Fuinjutsu's half the battle. And trust me, you're nowhere near ready for even basic—"
She stopped.
His expression. That faint, mocking glint in his eye.
The way he looked at her just then, almost daring her to finish.
Her breath hitched, and for the first time, she gasped, actually raising a hand to cover her mouth. "Don't tell me…" she said slowly, incredulously. "You've already dabbled in fuinjutsu?"
Ryusei let the two glows fade and lowered his hands.
His lips curved in that narrow, fox-like smirk. "Of course," he said. "And many other things."