Kakashi Masters All Elements, Rewrites the Ninja World for Rin!

"By the way, Minato-sensei. I heard from Sister Kushina that you were working on a Muji Ninjutsu… mind showing me the mystery weapon?"

Kakashi's voice was casual, but there was a glint of mischief in his eyes.

Minato looked up, smiling sheepishly."Oh, that... I haven't quite finished it yet."

But since Kakashi asked, he raised his right hand and showed the latest progress—a spiraling ball of chakra forming in his palm.

Kakashi squinted at it. "So, we're just… squishing chakra into a blue meatball?"

He tilted his head."The internal structure of forcibly compressed chakra must be unstable. When it blows up, are we just hoping it only hits the bad guys?"

Minato's smile stiffened slightly.

Kakashi wasn't wrong.

In the original records, the Rasengan was inspired by the Tailed Beast Bomb—an absurd technique where tailed beasts compress enormous amounts of chakra to the limit before launching it like a chakra nuke.

But humans, unlike walking chakra blobs, couldn't manage that kind of compression.

"Ahaha, yeah, that's exactly the problem," Minato admitted, scratching the back of his head.

He had tested the technique many times, but if he compressed chakra too much and detonated it in close quarters, the user would take the hit too.

If he threw it instead, the instability caused the ball to fall apart mid-flight. And reducing the chakra to maintain stability? That would defeat the whole point—he needed something explosive, a jutsu worthy of pairing with Flying Thunder God.

Kakashi crossed his arms. "What if you make the chakra spin? You know, rotate it in sync with your body's spin to stabilize it? Like stirring ramen... but more explode-y."

Minato's eyes widened in realization."Why didn't I think of that?! Kakashi, you're a genius!"

"Please, I prefer the term 'handsome genius.'"

Fueled by Kakashi's idea, Minato instantly began experimenting.

Three minutes later, the first Rasengan in history was born.

Minato vanished in a flash and reappeared beside a tree, pressing the spinning sphere into the trunk.

No explosion. Just raw, violent force—blasting a perfect hole through the center of the tree.

Kakashi raised an eyebrow, impressed.Yep. That's the Rasengan.

He nodded to himself. It wasn't that Minato lacked talent—it was just that his initial research path had gone sideways. Once aligned correctly, with a little sarcasm-fueled guidance, he nailed it in minutes.

"That worked faster than I expected!" Minato said brightly. "Kakashi, this technique was successful thanks to your help. Want to name it?"

Kakashi's eye twitched.

"Please don't say it..."

"How about... Spiral Flash Turbo Zero? No wait, Visiting Wind—"

"Ahem. Let's just go with Rasengan," Kakashi cut in quickly.

He imagined calling out "Spiral Flash Turbo Zero Bomb Jet Hurricane No. 3" in the middle of battle and sighed internally.

"Rasengan... that's a good name. But I still think—"

"Minato-sensei, I also made something new. Wanna see?"

Kakashi pulled out his secret weapon—the Ultimate Distraction Jutsu.

"Oh? Now I'm curious."

"Ox–Rabbit–Monkey," Kakashi muttered as he formed hand seals.

Electricity sparked in his palm.

"Chidori!"

A violent burst of lightning erupted from his hand, singing the air with high-pitched chirping as arcs of lightning crackled violently.

Minato's expression turned serious in an instant.

This was no child's toy.

The raw power, the instability, the cutting edge—this was a killing technique.

"Kakashi... you developed this by yourself?"

Kakashi gave a casual shrug."Yeah, kinda. Took about a week. I got bored."

"..."

Minato was speechless.

Two months to develop the Rasengan—with help—and his student made this in a week.

Who's the teacher again?

Still, the more talented the student, the better the teacher must be. Right?

That's the narrative Minato decided to stick with.

"No wonder you were obsessed with reaction speed training. This is what you were preparing for."

He smiled warmly.

"I was planning to teach you Rasengan so you could combine it with Flying Thunder God, like I do. But it seems like you've already carved out your own path."

"Give it a little time, and you might even surpass me."

"Minato-sensei… I actually already learned the Rasengan too."

Kakashi casually lifted his left hand and formed a nearly identical chakra sphere.

Minato blinked.

Wait… what?

You learned it just now!?

Over the years, Minato had seen many geniuses. But this? This was bordering on criminal levels of talent.

Maybe… just maybe… this kid was Hokage material.

"Minato-sensei? You're staring again."

"Huh? Oh, sorry, I was distracted."

Minato smiled again, this time with a hint of awe.

Kakashi then added, "I've been thinking about combining Chidori and Rasengan. You got any pointers?"

Minato's expression shifted instantly to serious.

"Fusion… huh."

"Rasengan is the pinnacle of chakra form change."

"And your Chidori is practically the ultimate in chakra nature change—specifically lightning release."

"Both are A-rank, high-tier techniques. If you can combine them successfully, you'll be looking at an S-rank technique. A true ultimate move."

"But it's extremely dangerous. Developing something like that without safeguards could seriously injure you."

He placed a hand on Kakashi's shoulder.

"If you really want to try this… let me be there. I want to make sure you're safe."

Kakashi looked away for a second, hiding the slight warmth in his eyes.

Behind Minato's ever-smiling face was a mentor who truly cared.

"Got it, sensei."