"Is this a ninjutsu you created?"
Tsunade looked at Minato with a face full of surprise, her eyes scanning the young boy as if seeing him for the first time. "And it was more than two years ago? When you were five?"
Minato smiled shyly, though his internal thoughts remained as cold and calculated as ever. "I just had good luck... I was playing with chakra and it just happened to take form."
"Incredible..."
Tsunade found it somewhat hard to believe. Since mastering the nature transformation of all five chakra elements, Minato had stopped practicing in the courtyard. Because there wasn't enough space for him to maneuver his high-speed movements, Tsunade wasn't very clear on the exact progress of Minato's strength.
"However, I see that this technique hasn't had nature transformation added to it; it probably isn't finished yet, right?" Tsunade looked toward Minato, her analytical mind already deconstructing the rotation of the blue sphere.
"Two years ago, that was the case. But over these two years, I have successively integrated the five types of chakra nature transformation into it, developing five different forms."
As Minato spoke, he extended his right hand. Chakra rapidly condensed in his palm, ultimately transforming into a blazing sphere of energy. Spiraling flames swirled around the sphere, which was deep red at its center, radiating a heat that made the air shimmer.
"For example, this one is the Dimensional Inspiration: Great Flame High-Explosive Rasengan, which has the Fire nature transformation added to it!"
"I see, Great Flame Rasengan!"
Looking at the chakra ball before her that radiated a lethal threat, Tsunade nodded in understanding, completely ignoring his overly long naming sense.
Minato subconsciously corrected her: "It's Dimensional..."
"Shut up, it's the Great Flame Rasengan!"
Tsunade glared at Minato, her patience for his eccentric names reaching its limit. "What's the attack effect?"
"Oh, it's an ultra-high temperature burst, accompanied by a super-strong explosive impact. It creates a vacuum of heat upon contact."
Minato answered honestly, then condensed a Rasengan with water ripples in his other hand, the blue energy spinning with a fluid, rhythmic motion. "In addition, there is the Water-attribute Raging Wave Tsunami Swirling Spiral Water Cannon!"
Tsunade snapped her fingers, her tone final: "Swirling Rasengan!"
Minato's tone carried a hint of negotiation, his facade of a passionate creator slipping into place: "Teacher, after all, this is a ninjutsu I developed... I should have some say in the branding."
Before Tsunade could say anything, Kushina gently tugged at the corner of Minato's clothes, whispering to him. "Minato, just listen to Teacher! Her names are much easier to say during a fight!"
Minato: "..."
"Hahahahaha~"
Hearing Kushina's words, Tsunade put her hands on her hips and laughed loudly, enjoying Minato's rare moment of speechlessness. "Come on, tell me what the names of the remaining ones are?"
"Wind Release: Rasenshuriken!"
Minato dispelled the water ball in his hand and condensed the Rasenshuriken. A piercing hum rang out, sounding like a thousand birds chirping, and a powerful gale quickly swept through the courtyard.
(The Rasenshuriken is not something that can only be thrown using Senjutsu; rather, a Rasenshuriken with $100\%$ completion can be used for long-range throwing attacks. Naruto only perfected the Rasenshuriken through Senjutsu; in the original work, Naruto used it more than once without Senjutsu.)
"Strange? Why is this name so normal?"
Tsunade looked at the Rasengan in Minato's hand, which closely resembled a shuriken in shape, and was suddenly surprised by the lack of dramatic flair.
"Because it looks like a shuriken, and it can be thrown just like one. It's practical."
Minato smiled; he couldn't very well say that this was a ninjutsu created by his future son and that he needed to respect the copyright.
Dispelling the Rasenshuriken, two special Rasengans, one blue and one yellow, appeared in his hands. The blue one flickered with threads of electricity, while the yellow one looked simple and unadorned, heavy with dense energy.
"Additionally, there is the God-Speed Stealth Raid Myriad Roaring Thunder Burst Rasengan! It can be thrown and can even enter an invisible state by vibrating the air!"
"Lightning Release: Thunderstorm Rasengan!"
"Super Powerful Overlord Impact Mountain-Shaking Spiral Cannon! It can also be fired, has a super-strong impact, and can easily blow up a small mountain!"
"..."
Hearing these names, Tsunade felt her temples throbbing from the sheer absurdity of the titles. "Let's just call it... Earth Release: Mountain-Shaking Rasengan."
Minato fell silent, looking as if he had lost all color, his head drooping in mock disappointment.
"Hahahahaha!"
Seeing Minato like this, Tsunade laughed even more wildly. She felt that Minato was inexplicably cute this way, making her unable to resist wanting to bully him ruthlessly.
"The name doesn't matter! More importantly! Minato! Can you teach me?"
Nawaki grabbed Minato's arm, his eyes burning with a desire for power. "I have Water and Earth chakra attributes. Either one, just teach me! I want to blow up mountains too!"
Minato said in a faint tone, his internal coldness returning: "You just need to integrate the chakra nature transformation into the Rasengan. It's a matter of balance and focus."
Nawaki fell into a brief silence, his excitement stalling as he realized the difficulty. So, how exactly do you cultivate chakra nature transformation?
Kushina tugged at Minato's sleeve, her eyes filled with a hint of anticipation and a bit of shyness. "Minato, can I learn this ninjutsu? I want to be able to fight alongside you."
"Of course!"
Minato nodded. If he remembered correctly, this technique was originally developed by his original self for Kushina. It was only fitting she learn it now.
"Yay!"
Kushina cheered, her mood instantly brightening.
"Speaking of which, how did you think of creating this ninjutsu?" Tsunade asked curiously, still fascinated by the mechanics of the spinning orb.
"I was inspired while watching a washing machine work."
Someone finally asked. Hearing Tsunade's question, Minato pulled out the explanation he had prepared long ago, delivered with a perfectly straight face.
"Once, the washing machine at home broke. I discovered that if the water didn't spin out during the spin cycle, the washing machine would constantly vibrate and even move due to centrifugal force. I thought, what if I could replicate that force with chakra?"
"I see..."
Tsunade nodded. This reason actually made sense to her, as many great discoveries came from observing daily life. "I didn't expect that just doing laundry could allow you to create a ninjutsu of this caliber."
"Washing machine..."
Nawaki's mouth twitched as he looked at his own hands. "I've watched the washing machine do laundry plenty of times, so why didn't I see any hidden logic? I must be a different kind of genius."
"It was just... a stroke of luck. A moment of clarity."
Minato laughed awkwardly. Compared to the inspiration gained from observing a Tailed Beast Ball in the original work, the washing machine reason was a bit of a letdown, but he couldn't think of any other more suitable reason that wouldn't reveal his past life.
"Then for the special training later, can you teach us the cultivation method for nature transformation?" Nawaki hurriedly followed up, eager to progress beyond the basic form.
Minato nodded: "Of course, but before that, you all still have to pass the trap assessment. Mastery of power is useless if you are caught in a snare."
"Again?"
Nawaki wailed. He now felt nauseous just looking at an exploding tag, the scent of gunpowder triggering a Pavlovian response of dread.
Minato smiled. The training for dodging traps was non-negotiable! As the saying goes, only those who survive are worthy of dealing damage!
Furthermore, because of the changes in the Land of Rain, the originally scheduled special training time had been drastically shortened. For this reason, he had specifically sent a clone to the training ground this morning to increase the difficulty of the traps and mechanisms to $200\%$ of their previous levels.
The traps he had set previously could only be considered medium difficulty at most. For an experienced ninja, they could be seen through at a glance.
But now, with the increased difficulty and the density of the traps, even an experienced Jonin would have to take a couple of exploding tags if they weren't careful.
In the following days, all four began high-intensity special training. Nawaki and the other two continued their grueling training of traversing the trap zones, their bodies becoming a map of small cuts and bruises.
Meanwhile, Minato began his long-prepared physical body cultivation. He knew that while his fruit powers were great, a strong physical vessel was required to handle the maximum output of light-speed movement.
Recently, both his appetite and strength had been surging. Minato felt that he should be entering his growth period, which was the perfect time to cultivate his physique.
So, he had someone forge a set of full-body weights and a solid steel sphere with a diameter of one meter, weighing approximately $4,000$ kilograms.
The moment the steel ball was hung in front of the valley entrance by several reinforced vines, Kushina and the other two gathered around curiously, marveling at the sheer mass of the object.
Kushina asked curiously: "Minato, Minato, what is this? It looks so heavy!"
"Cultivation equipment," Minato said simply, adjusting the seals on his wrists.
"Cultivation equipment? Hmm—"
Nawaki tilted his head, trying to push the ball with one hand and finding it wouldn't even budge. "Is this... a weight? Are you going to lift it?"
"No."
Minato stepped forward slowly, the gravel crunching beneath his feet. He dropped into a horse stance, sank his Qi into his dantian, and then slammed a punch into the steel ball!
CLANG—!!
Under the dumbfounded gaze of the three, the steel ball immediately let out a sky-shaking sound that echoed through the valley. It was actually sent flying by Minato's punch, the impact creating a visible shockwave in the air!
The massive steel ball snapped the thick vines like they were threads and became deeply embedded in the rock wall of the mountain, leaving a massive crater.
Gulp...
Nawaki swallowed hard, his eyes wide as saucers. "Is this... Sister's Monstrous Strength? Did you learn her secret technique?"
Blood dripped from Minato's fist, the skin split by the force of the collision, yet his tone was very calm, his heartbeat steady. "No, this is pure strength without any chakra! It is the result of forcing the body to transcend its limits."
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