The sun shone brightly beneath a cloudless blue sky.
Konohagakure's Training Ground No. 4.
BOOM!!!
A deafening roar erupted without warning, like the earth's veins exploding beneath the ground.
The solid terrain at the center of the training ground suddenly caved in, cracked apart, and buckled upward. A massive, irregular crater more than five meters across appeared out of nowhere. Dust and countless chunks of shattered rock shot skyward like a fountain before raining back down with a series of sharp clatters.
Watching from the sidelines, Kurenai and Shizune instinctively took two steps back. Both swallowed nervously, their faces filled with shock.
Tsunade-sensei... she's actually serious this time!
The same thought flashed through both girls' minds as they exchanged glances.
They had always known how terrifying Tsunade's Monster Strength was, but in the past, their teacher had only demonstrated it in moderation or used it during instruction.
When had they ever seen anything like this?
One punch that nearly overturned half the training ground?
Inside the field, the blonde figure responsible for the devastating attack—Tsunade—didn't pause for even a moment. Chakra erupted beneath her feet once again.
Bang!
A shockwave exploded from the ground.
Like a golden cannonball, Tsunade launched herself forward with overwhelming speed and power, tearing through the air with a piercing shriek as she charged straight toward the black-haired boy in the distance—Higashino Shinichi.
The air distorted visibly around her advance. The sharp sonic boom made onlookers' eardrums ache.
Yet in the face of Tsunade's relentless assault, as overwhelming as a collapsing mountain or a raging tsunami, Shinichi remained remarkably calm.
He moved with fluid, almost serpentine grace.
His footwork was elusive and unpredictable, as graceful as drifting snow carried by the wind.
Step!
Turn!
Pivot!
Shift!
His movements seemed to merge seamlessly with the flowing air around him. Every action carried an indescribable lightness and elegance.
Even more astonishing was what happened to the air itself as he moved.
The wind resistance and turbulent airflow that should have hindered high-speed movement appeared to be guided and tamed by some invisible force. Rather than becoming obstacles, they subtly transformed into sources of momentum and lift.
Every sidestep, twist, and gliding movement appeared meticulously calculated, keeping him precisely at the edge of Tsunade's striking range.
His actual movement speed didn't seem particularly fast.
Yet combined with prediction so precise it bordered on the impossible and an extraordinary ability to borrow force from his surroundings, he always managed to evade Tsunade's devastating blows at the very last moment.
A hair's breadth.
Again and again.
Dangerous!
Dangerous!
Dangerous!
The wind pressure from her fists brushed past his clothes, making them snap loudly.
The ground continued exploding into fresh craters under Tsunade's relentless pursuit.
Yet Shinichi remained like a leaf drifting in a storm—unstable, elusive, impossible to pin down.
Not once had he been struck directly.
This wasn't merely supreme control over his body and footwork.
It was an astonishing level of environmental awareness and utilization.
Shizune and Kurenai stared with wide eyes, scarcely daring to breathe.
They had never seen such a graceful yet perilous style of movement.
This had already gone far beyond ordinary taijutsu or Body Flicker Techniques.
It looked more like an art form that fused exceptional perception, exquisite chakra control, and a unique philosophy of movement.
"Oh?"
After several attacks missed their mark, Tsunade finally slowed her pursuit.
A trace of surprise flashed through her eyes.
Stopping in place, she let out a cold snort.
"Aren't you supposed to be Crimson Flame Shinichi? Where's your Fire Release Nintaijutsu?"
The reason for the sparring session was simple.
Several days earlier, Jiraiya had returned to the southwestern front to resume command. At the same time, Sunagakure's increasingly disastrous offensive had noticeably slowed, especially since Chiyo—the infamous poison master—had vanished from the battlefield for an extended period.
After fighting continuously on the southwestern front for half a year, Tsunade had finally been able to catch her breath.
She returned to the village alongside a batch of Konohagakure shinobi who also required rotation and rest.
Then, on the very day Team 10 reassembled, Tsunade had barely exchanged greetings before launching a practical combat test.
Her reason?
"I heard you've made quite a name for yourself on the northeastern front and pulled off some earth-shattering feats."
And thus, the current scene had come about.
Hearing her question, Shinichi stopped as well.
"Tsunade-sensei, here's the thing."
"Recently, I've run into a bottleneck in the development of my Fire Release Nintaijutsu. Continuing to explore a purely fire-based path doesn't seem likely to produce a qualitative breakthrough anytime soon."
"So I started wondering whether I could gain inspiration from the properties and applications of other chakra natures."
"Especially Wind and Fire. Wind naturally fuels flames, while fire borrows strength from the wind. The two are inherently connected."
"If I can achieve meaningful progress with Wind Release, it may help me break free of some fixed patterns in my Fire Release research and open up entirely new directions for future development."
A bottleneck?
Do you even hear yourself?
In less than two years, starting from nothing, he had independently developed a Fire Release Nintaijutsu system that had astonished the entire shinobi world.
He had even defeated the Third Raikage head-on in battle—the man known as the "Strongest Shield."
And now, after such a short time, he was calmly talking about having hit a bottleneck?
To Tsunade, it felt like someone had just climbed a mountain that ordinary people could only dream of reaching, glanced at the scenery from the summit, then frowned and said to those still below:
"This mountain feels a little short. Climbing it wasn't satisfying enough. I'll stop for now and go find another mountain for inspiration."
For a moment, Tsunade genuinely didn't know what to say.
Taking a deep breath, she suppressed the urge to complain and refocused on the matter at hand.
"So this is the result of your recent Wind Release research?"
"Yes, Tsunade-sensei."
Shinichi nodded.
"I call it Swift Step."
"It's a movement technique that deeply integrates the characteristics of Wind Release chakra with traditional Body Flicker Techniques."
"By combining acute perception of surrounding airflow with precise interference and control, it creates a highly flexible movement style with extremely low chakra consumption."
The Swift Step that Shinichi developed had clear limitations.
In terms of short-distance, instantaneous burst speed, it was far inferior to the Flame Burst Step of his Fire Release Nintaijutsu.
For long-distance, sustained high-speed movement, it was likewise nowhere near the level of the Lightning Body Flicker used in Kumogakure's Lightning Release Nintaijutsu.
However, Swift Step possessed advantages that neither of those techniques could match.
First, its unparalleled lightness and flexibility.
Swift Step focused on rapid directional changes within a small area, precise repositioning, and exceptional adaptability to complex terrain. In close-quarters combat, when evading localized attacks, or when maneuvering through environments filled with obstacles, the mobility advantages granted by Swift Step were far beyond the reach of either Flame Burst Step or Lightning Body Flicker.
Second, its remarkable stealth and silence.
Swift Step could cleverly guide, smooth out, and even utilize the turbulent airflow generated by movement, minimizing both wind-breaking sounds and atmospheric disturbances to the greatest extent possible. This made it exceptionally suited for infiltration, covert operations, and silently approaching a target.
"Swift Step?"
After hearing Shinichi's explanation, Tsunade raised an eyebrow.
"Does it have anything to do with Pakura's Swift Release?"
Shinichi froze for a moment before shaking his head.
"Probably not. They just happen to share the same word."
That was what he said, but his thoughts inevitably drifted back to his previous battle against Pakura.
The way she had approached him in near-total silence, as though she had merged with her surroundings.
The unnatural lightness and agility she displayed during combat, seemingly defying normal physical inertia.
And the sudden bursts of acceleration she occasionally unleashed.
Could Pakura's so-called Swift Release actually be a unique composite application technique that combines the lightness of Wind Release with the explosive power of Fire Release through some special method?
That would explain why her speed possessed both silent agility and explosive acceleration—two qualities that seemed contradictory at first glance, yet blended together perfectly.
After all, her Scorch Release was a fusion bloodline limit created from Wind and Fire.
The thought stirred something within Shinichi.
Tsunade, however, seemed to have asked only out of casual curiosity and had no intention of pursuing the matter further.
She snorted lightly.
"Then let me see just how much you've managed to figure out about Wind Release during this time!"
The moment the words left her mouth, Tsunade stopped holding back.
She exploded forward once again.
This time, her speed was noticeably faster than at any previous point in the fight.
Her fist tore through the air as it came crashing toward Shinichi.
Shinichi's eyes sharpened as he rode the airflow backward, narrowly avoiding the incoming punch. With a quick turn and shift, he had already repositioned himself more than ten meters away.
The instant he stabilized his footing, his counterattack arrived.
A condensed pale-cyan wind blade, so dense it seemed almost tangible, burst from the edge of Shinichi's leg and slashed forward with a piercing howl.
Storm Blade!
"Heh. You've got quite a few tricks."
A flash of interest appeared in Tsunade's eyes.
She neither dodged nor retreated.
Instead, she simply threw a punch.
A visible white shockwave exploded from her fist and slammed directly into the incoming Storm Blade.
BOOM!!
The collision between shockwave and wind blade produced a thunderous explosion.
Violent winds swept across the training ground. Scattered blade fragments and chaotic air currents carved shallow grooves into the earth.
Bang! Bang! Bang!
Several more rounds of lightning-fast exchanges followed.
The pace of offense and defense shifted so rapidly that it was nearly impossible to follow.
Yet Tsunade, with her vast combat experience and overwhelming strength, seemed to be gradually grasping the patterns and rhythm behind Shinichi's Swift Step.
Suddenly, she raised her right leg high into the air and stomped down with all her might.
RUMBLE!!!
It was as if a meteor had struck the earth.
Centered on the point of impact, the ground within a radius of dozens of meters violently overturned and shattered like a fragile eggshell.
Countless chunks of rock and soil erupted skyward.
A savage shockwave and earthquake-like tremor expanded outward in every direction.
Faced with such a catastrophic transformation of the battlefield and an all-encompassing barrage of impacts, even Shinichi's agile footwork inevitably suffered the slightest hesitation.
And that single moment of hesitation was all Tsunade needed.
Using the tremendous recoil force generated by her own attack, she accelerated once more, instantly closing the distance between them.
Heavenly Foot of Pain: Charge!
Over the past year and a half, Shinichi hadn't been the only one learning from Tsunade.
Tsunade had also gained valuable insights from her student.
After observing Shinichi's Flame Burst Step, she had developed a movement technique that perfectly complemented the characteristics of her Monster Strength.
A method of instantaneous burst acceleration.
Heavenly Foot of Pain: Charge!
By using the principles behind Monster Strength to concentrate chakra in her legs, she generated an overwhelming propulsive force.
BANG!
A dull impact, like a giant warhammer striking a massive drum, echoed throughout the training ground.
Tsunade's punch landed squarely against Shinichi's crossed forearms.
The force sent his entire body flying backward like a kite with its string cut.
Yet at that very moment, while Shinichi was hurtling uncontrollably through the air, something strange happened.
The chaotic air currents raging around him from his rapid flight suddenly seemed to come alive.
As though infused with will and purpose, they swiftly gathered, separated into layers, and began circulating in an intricate pattern.
Like countless invisible yet gentle hands, they softly supported his airborne body.
The speed of his backward flight rapidly diminished in a manner that seemed to defy the laws of physics, becoming increasingly gentle, as though he had fallen into an invisible cushion of elastic air.
Then something even more unbelievable happened.
Under the astonished gazes of Tsunade, Shizune, and Kurenai, Shinichi's figure came to a complete stop more than ten meters above the ground, hovering steadily in midair.
"H-He... he's flying?!"
Shizune's eyes widened as she blurted out the words in disbelief.
Beside her, Kurenai covered her mouth in shock.
Even Tsunade stopped her pursuit.
She looked up at Shinichi, who floated calmly in the air while faint streams of airflow swirled around him like miniature vortices.
With obvious interest, she asked, "You little brat, what's this supposed to be now? Another one of your Wind Release creations? You can actually fly?"
Hovering in midair, Shinichi nodded.
"Yes, Tsunade-sensei."
"I call this technique Sky Dance."
"The core principle is to continuously and stably distribute Wind Release chakra across the surface of the body. Through precise control of the interaction between my chakra and the surrounding air, I can remain airborne, hover, and even move through the sky."
As he spoke, Shinichi shifted his body slightly.
Subtle ripples spread through the surrounding air, so faint they were almost impossible to detect with the naked eye.
"That said, the technique still lacks stability. Its speed and maneuverability in the air are also far inferior to movement on the ground, so its practical combat value is currently limited."
"For now, it's more of a tactical option."
"For example, it can be used to avoid certain ground-based attacks or to gain a better field of view."
"You really do keep coming up with new tricks."
Tsunade stared at the hovering Shinichi, her tone complicated.
He made it sound simple.
But Tsunade understood better than anyone the strategic significance of flight itself.
The ability to freely soar through the sky was practically equivalent to possessing an innate tactical and survival advantage in the vast majority of battles.
Advance when desired.
Retreat when necessary.
Whether it was reconnaissance, surprise attacks, flanking maneuvers, or disengagement, an aerial combatant enjoyed conveniences that ground-based shinobi simply couldn't match.
Looking across the entire shinobi world, there seemed to be only one person capable of flight through his own abilities.
The Third Tsuchikage, Ōnoki.
"Alright, alright. Stop showing off up there and come down. This test is over."
Tsunade waved her hand impatiently, signaling for Shinichi to quit floating around and get back to the ground.
Then she turned toward Kurenai and Shizune, who were cautiously approaching.
"You two need to keep working hard as well."
"Don't let this brat leave you too far behind."
"At the very least... don't get left so far behind that you can't even see his shadow anymore."
That was what she said.
But Tsunade herself knew it was mostly a line meant to encourage the two girls.
If ordinary geniuses needed to reach Kakashi's level just to meet the threshold of a true prodigy...
Then Kakashi-level prodigies were merely the threshold required to stand in the same category as a once-in-a-generation monster like Shinichi.
Even her grandfather, the man revered as the God of Shinobi—Senju Hashirama—probably hadn't possessed strength anywhere near what this kid was displaying at the same age.
Wait...
What exactly had Grandpa been doing at this age?
Tsunade suddenly drifted off in thought.
Fragments of childhood memories surfaced—occasional stories her grandmother Mito had told her while chatting casually.
If she remembered correctly...
Hadn't Mito once mentioned that at this age, her grandfather used to spend his time by the river with a friend, competing to see whose skipping stone could bounce farther and more times across the water?
As for who that friend was—the one who had played such childish games with her grandfather—
Mito hadn't gone into detail.
Or perhaps young Tsunade simply hadn't paid attention.
Probably some ancestor from the Senju Clan.
It couldn't possibly have been Uchiha Madara... right?
Shaking off the stray thoughts, Tsunade refocused her attention on Shinichi.
"Alright, enough of that."
"How's your research into the Yin Seal scroll I gave you?"
"Have you run into anything you don't understand?"
"As for the Yin Seal, Tsunade-sensei, let's talk about that later."
A faint smile appeared on Shinichi's face.
He reached into his robes and pulled out a small, exquisitely crafted scroll before handing it over.
"Take a look at this first."
Tsunade raised an eyebrow.
She accepted the scroll and casually began undoing the sealing formula wrapped around it.
At the same time, she muttered with mild curiosity, "And what's this supposed to be? What have you cooked up this time, you little—"
"Hm?!"
Before she could finish speaking, her voice abruptly cut off.
As the scroll was fully unrolled, a soft, pure pale-green glow suddenly blossomed from within it, radiating a rich aura of life and healing chakra.
"This is—?!"
Tsunade froze.
Her eyes widened instantly.
Then she snapped her head up toward Shinichi and exclaimed in disbelief, "A Healing Technique?! You actually succeeded in sealing a Healing Technique inside a scroll?!"
Throughout the shinobi world, sealing scrolls were primarily used to store inanimate objects, ninjutsu, or corpses that no longer possessed signs of life.
They could not seal living beings or anything that carried a living life force.
Medical ninjutsu, meanwhile, fundamentally involved converting one's Yang Release chakra into life energy capable of healing, revitalizing, and repairing the body.
Perhaps precisely because this energy was so highly active, no one had ever managed to create a sealing scroll capable of stably storing a completed medical ninjutsu and releasing it on demand.
Yet now, the scroll Shinichi had handed her shattered that conventional wisdom.
Seeing the shock on Tsunade's face, Shinichi explained, "Yes, Tsunade-sensei."
"I remember you mentioning before that one of your long-held goals was for every shinobi squad in Konohagakure to eventually have a dedicated medical ninja."
"That way, casualties during missions could be reduced as much as possible and more comrades' lives could be saved."
"But with the current training system in Konoha—and throughout the entire shinobi world—that goal remains a long way off. There are simply too many practical obstacles."
"After all, training a qualified medical ninja is extraordinarily difficult."
"So I started wondering whether there might be another approach."
"If producing competent medical ninjas requires a long training period and the numbers remain limited, then perhaps we could take a step back and pursue a different solution."
"What if every squad—or even every individual shinobi—could at least carry a disposable medical-ninjutsu scroll capable of saving lives in an emergency?"
Shinichi pointed at the scroll.
"This is the result of some preliminary experimentation based on that idea."
"When activated, it requires only a small amount of chakra to trigger the formula and release a standard Healing Technique."
"It can be used for emergency treatment of external injuries and for stabilizing wounds."
"Of course, this is only a very primitive first-generation prototype."
"The effect is inferior to having a medical ninja perform the technique personally."
"The production cost is high, the process is complicated, and stable mass production isn't currently possible."
"After all, I'm still only a beginner when it comes to fūinjutsu. There are many theoretical problems I haven't solved yet, and process optimization is even further away."
Then Shinichi smiled.
"So, Tsunade-sensei..."
"As the strongest medical ninja in the shinobi world, would you be interested in joining my research?"
It was a pity that the shinobi world didn't have anything like a Nobel Prize.
Otherwise, with a revolutionary invention capable of transforming the entire medical landscape, he could easily win a prize in physiology and medicine.
Then another thought crossed his mind.
No Nobel Prize?
That was fine.
When the time was right, he could simply create a Higashino Shinichi Prize himself.
It could be awarded specifically to individuals whose inventions and discoveries advanced technology throughout the shinobi world or significantly improved people's lives.
Not only would that further expand his reputation and influence, but it would also allow him to guide the development of the entire shinobi world and drive the collective consciousness of the age in the direction he desired.
Tsunade stared blankly at the boy before her.
She had only mentioned that dream once in passing during a moment of reflection.
Yet he had remembered it.
Not only remembered it, but had already begun trying to solve a problem that had troubled the shinobi world for countless years using his own methods.
A warm feeling stirred within her heart.
Without a second thought, she shouted, "Interested?! Of course I'm interested!"
"Right now!"
"Immediately!"
"Let's go, let's go, let's go!"
She stepped forward and reached for Shinichi's arm, intending to drag him straight to the laboratory.
After only two steps, however, she suddenly realized something and came to an abrupt halt.
Turning around, she looked at Kurenai and Shizune, who were still standing there in a daze.
"What are you two standing around for?!"
"Hurry up and come with us!"
"This is something that could change the future of the entire shinobi world!"
At their current level, neither Shizune nor Kurenai possessed sufficient expertise in medical ninjutsu or fūinjutsu to contribute to the core research itself.
But as assistants?
Recording data, processing materials, and carrying out basic experimental procedures would be more than within their capabilities.
More importantly, this was the perfect opportunity to participate in cutting-edge research and learn through direct practical experience.
"O-Oh... yes, Tsunade-sensei!"
The two girls finally snapped out of their stupor.
Responding hurriedly, they broke into a run and followed after them.