Chapter 169
To complete the Lightning Release: Rasengan Railgun, Kiriya returned to the research notes left behind by Senju Tobirama.
Tobirama was famous for his Water Release, largely because it gave him an advantage against the Uchiha clan’s Fire Release, but water had never been his only specialty.
He possessed all seven chakra natures and had conducted extensive research into wind, fire, lightning, water, and earth.
Kiriya used those notes as a foundation, testing every theory through practice as he steadily refined his lightning-nature transformation.
That was only part of the work.
He also had to study electricity, mechanics, and a mountain of formulas before the technique could function the way he imagined.
This proved to be the most time-consuming stage.
Before transmigrating, Kiriya’s understanding of physics had barely reached middle-school level—and he had long since returned most of that knowledge to his teachers.
Fortunately, he was no longer the person he had once been.
Awakening the Three-Tomoe Sharingan had greatly improved both his perception and his ability to process information.
On top of that, Strong One’s Wish constantly enhanced his concentration and learning efficiency.
Compared with his past self, he could absorb information at a ridiculous pace.
The real obstacle was building a stable model for the technique.
When developing Wind Release: Rasenshuriken, Kiriya had Naruto’s completed technique as a reference.
He only needed to understand the principles and reproduce them.
This time, he was working from nothing.
He had to add lightning-nature transformation to the Rasengan while also creating an electromagnetic acceleration system capable of launching it.
Every additional mechanism multiplied the complexity.
To speed things up, Kiriya created more shadow clones to help with the research.
He also sought outside assistance.
Specifically, Gojo Satoru.
"Lightning Release: Rasengan Railgun?"
Gojo became visibly interested the moment he heard the idea.
"A completely new technique?"
In the jujutsu world, innate techniques were determined at birth.
A sorcerer could improve their control and develop new applications, but creating an entirely new power from the ground up was considered impossible.
Kiriya intended to do exactly that.
The opportunity to study chakra, nature transformation, and a completely foreign energy system made the project both challenging and irresistible to Gojo.
He agreed almost immediately.
The two often lost all sense of time as they discussed theoretical structures, constructed models, and repeatedly tested whether their calculations were viable.
With the Six Eyes, Gojo possessed an overwhelming advantage in analyzing energy and processing data.
Kiriya could not hope to match him in that area.
Without that level of perception, no one could have controlled an absurd technique like Limitless in the first place.
With Gojo’s help, progress on the theoretical side accelerated dramatically.
Unfortunately, theory was only the beginning.
Turning those calculations into a working technique remained extremely difficult.
Both lightning-nature transformation and the construction of the electromagnetic field consumed enormous amounts of chakra.
After only two or three attempts, Kiriya had to stop and meditate until his reserves recovered.
The compressed sphere of lightning was also violently unstable.
It often exploded halfway through formation, destroying shadow clone after shadow clone.
Using clones spared Kiriya’s real body from catastrophic injury, but every time one vanished, the memories and pain returned to him.
Repeatedly experiencing his own body being torn apart was far from pleasant.
Even so, Kiriya refused to quit.
If anything, every failure only made him more stubborn.
He lowered his head, clenched his teeth, and kept going.
Even Gojo eventually gave him an approving thumbs-up.
The kid had spirit!
...
Two months later, Kiriya and Gojo stood side by side on a remote island, looking toward a mountain nearly a kilometer away.
Its summit rose more than a hundred meters into the air.
"You ready?" Gojo asked.
"Yeah."
Kiriya nodded excitedly.
The technique was almost complete.
Today, he would finally see whether the last two months of work had paid off!
"Then let’s begin."
As soon as Gojo spoke, Kiriya created a shadow clone.
The original extended his right hand and began forming a Rasengan, while the clone carefully introduced lightning-nature transformation into the rotating sphere.
"Clones really are convenient."
Gojo watched with open envy.
"Independent minds, the same knowledge as the original, and almost all the same abilities. Aside from having less energy and being easier to destroy, it’s basically another version of yourself."
Unfortunately, Limitless naturally rejected most foreign energy systems.
Otherwise, Gojo would absolutely have learned the technique for himself.
After several seconds, the sphere stabilized.
It rotated at extreme speed, arcs of lightning crawling across its surface.
The violent electrical energy had been compressed and restrained within the Rasengan, giving it a deeply destructive presence.
"Good."
Kiriya focused.
"Now for the acceleration field."
Lightning surged around his body.
One electromagnetic field after another formed in front of him, combining into a launch rail similar to an electromagnetic weapon.
The instant the structure was completed, the Rasengan vanished from his hand.
It had accelerated so quickly that even Kiriya’s enhanced vision caught only the faintest trace of movement.
At almost the same moment, the distant mountain was engulfed in blue-white light.
Its enormous, solid mass crumbled from the inside out, breaking apart piece by piece until much of it simply disappeared.
BOOM!
Only then did the sound reach them.
The shock wave struck the island with the force of a powerful hurricane.
Trees across several kilometers snapped or were torn from the ground, while waves several meters high rolled across the sea.
"Wow."
Gojo raised one hand above his bandaged eyes and studied the destruction.
"That’s extremely impressive."
Then he turned toward Kiriya and sighed.
"The only problem is the stamina cost. Kiriya, a man really shouldn’t run out of energy that quickly."
Kiriya stood with both hands braced against his knees, sweat pouring down his face.
That single shot had consumed nearly half his chakra.
He glared at Gojo.
"Shut up. Not everyone was born with cheats like the Six Eyes and Limitless."
He cast Yang Power: Everflowing Vitality on both arms.
The unbearable numbness and sensation of his flesh being sliced apart gradually faded.
"I’m serious," Gojo said, his voice quieter now. "Don’t use a technique like that unless you absolutely have to."
"You should also prepare an escape plan. Once you fire it, you’ll be vulnerable. There are plenty of sorcerers who’d happily wait for that moment and stab you in the back."
Kiriya nodded.
Gojo was right.
If this were his only trump card, he would need to be extremely cautious about using it.
Fortunately, it was not.
As his mastery improved, the chakra cost would continue to fall.
He also possessed Sage Mode, which greatly expanded his effective reserves and improved his precision.
While using senjutsu chakra, he could probably fire four or five shots and still retain enough strength to continue fighting.
And if everything went wrong, there was always Flying Thunder God.
He could retreat, recover, and return for a second round.
Or a third.
Eventually, someone would run out of strength.
Kiriya had no intention of being the first.