Chapter 15 — Burn! Burn! Burn!
Three days later.
Inside a classroom on the first floor of Kyoto Jujutsu High, during a break between lessons—
"Burn."
With a soft whoosh, a flame leapt to life at Ren's fingertips.
"…H-how is that possible?"
The three people standing in front of him were completely stunned.
The one who found it hardest to accept was Mai.
After all, "In over a thousand years of jujutsu history, no one has ever learned an innate technique through postnatal effort."
That was a fact she firmly believed in—one she had used again and again to try to dissuade Ren.
And yet, the vivid crimson flame blazing in the boy's pale palm was just as undeniable a fact.
Mechamaru's metal face showed no expression, but the way his body had gone completely rigid made his shock obvious.
Strangely enough, the one who looked the least shaken was Miwa Kasumi, despite normally being the most tightly wound of the group. Still, judging by her slightly parted lips, even she was far from calm.
What Miwa hadn't said out loud was that she'd always believed in Ren.
Among the three of them, she alone had truly felt—firsthand—just how terrifying his talent for cursed energy manipulation was.
But even so…
She never imagined it would happen this fast.
In her mind, this was supposed to be a someday story.
Ren would spend ten years—maybe decades—obsessively researching and refining his understanding. And then, on some distant future day, all that effort would finally bear fruit. He would accomplish the unprecedented feat of learning an innate technique after birth and become a legendary figure recorded in jujutsu history.
And yet—
This history-defining miracle…
He'd done it in three days.
"…No way. How did you pull this off?"
Mai asked, barely able to contain her shock.
"It was pretty simple," Ren said lightly.
He snapped his fingers, casually extinguishing the flame dancing between them, his smile bright and untroubled.
"I just used the Limitless Probability Technique to eliminate every incorrect possibility among several million faulty hypotheses—until only the single correct answer remained."
...
"Teach me."
Having finally recovered from the shock, Mai blurted it out without hesitation.
She had always despised her own useless technique.
Her Construction Technique was infamous for its abysmal efficiency. Even creating the smallest, simplest object consumed an absurd amount of cursed energy. And to make matters worse, due to certain reasons, her total cursed energy reserves were far lower than those of most sorcerers.
The result?
An utterly ridiculous situation where she could barely manage to construct one bullet per day.
When Ren complained about the inefficiency of his Limitless Probability Technique, Mai had actually understood him better than anyone.
Because compared to her—
His "problem" sounded downright luxurious.
---
She had dreamed of it countless times.
What if the technique she possessed hadn't been Construction—what if it had been something more efficient?
Something better suited to her?
Even with her thin reserves of cursed energy, would she have had a chance to become a truly capable jujutsu sorcerer?
She would have been willing to give up anything in exchange for a technique with better compatibility.
And now—
That dream had actually appeared right in front of her.
An opportunity to change her technique.
There was no way she could let it slip away.
No matter what Ren asked for, as long as it meant she could learn this technique, she was willing to agree.
"R–Ren…"
On the other side, Miwa Kasumi spoke up just as urgently.
Deep down, her longing for an innate technique burned even hotter than Mai's.
Mai at least had a technique—even if it was inefficient.
Miwa, on the other hand, had none at all.
For a jujutsu sorcerer, that was the deepest, most painful flaw imaginable.
She dreamed of having her own technique—of becoming a sorcerer who was truly qualified to stand on the battlefield.
And now, a chance to obtain one lay right before her eyes.
There was no way she could give it up.
If—if she could master a technique…
Her heart raced with hope.
Maybe her rank would improve.
Maybe she'd be allowed to take on higher-level curses.
Maybe she could earn more money.
And if that happened… her younger brothers' lives would finally get better.
"C–can I learn it too?"
She asked softly, carefully, as if afraid that this entire moment was nothing more than a fragile dream that would burst at the slightest touch.
"Of course," Ren replied without hesitation, nodding naturally.
If he could learn it, then others could too.
That was the entire point of his research—to make innate techniques something that could be acquired after birth.
Seeing the intensity burning in both girls' eyes, he didn't waste any time. He immediately began explaining his understanding of the Flame Technique.
But as he spoke, he quickly realized something.
His success wasn't solely because he could use the Limitless Probability Technique to eliminate incorrect possibilities.
More importantly—
He possessed the qualifications to learn.
Twelve times the cursed energy control precision of an ordinary person.
Twelve times the cognitive processing ability.
In other words, the Limitless Probability Technique merely shortened the trial-and-error process.
The real threshold—the true requirement for learning a technique—was his overwhelming precision and intellect.
And those were things neither of the two girls possessed.
After just a few minutes, the excitement on Mai and Miwa Kasumi's faces began to fade, replaced by confusion… then doubt.
A few minutes later, those doubts had thickened into heavy clouds hanging over their delicate faces.
When Mai finally raised her hand and called out, "Stop," Ren had no choice but to start over—this time explaining everything again in what he believed was a simpler, more intuitive way.
It didn't help.
The confusion on their faces only deepened.
Half an hour later, Mai was the first to surrender.
Sweat beaded on her forehead as her eyes spun slightly. She looked at Ren and said weakly,
"Ren… is it possible that this whole 'learning an innate technique after birth' thing only works for you?"
"We're not like you. We don't have brains that run at twelve times the capacity of a normal person."
"M–maybe…"
Ren hesitated, then scratched his head.
"I can try explaining it again. Even more slowly. Even more fundamentally—"
"No…"
Mai let out a long breath, nausea rising in her chest.
"Let's… let's stop here for today. If I listen any longer, I think I'm going to throw up."
She struggled to stand, pushing herself up from the desk.
"I need to… go back to the dorms and sleep. Immediately."
"…Alright," Ren said helplessly.
He turned toward Miwa, preparing to say goodbye as well.
As for Mechamaru, he'd already left earlier—apparently, his own technique was powerful enough that he wasn't particularly interested in this kind of research.
But to Ren's surprise, Miwa didn't leave.
She bit her lip lightly, clearly nervous, yet stubbornly resolute.
"Ren… c–could you explain a little more to me?" she asked quietly.
"I feel like… I can still hold on."
Ren blinked—then broke into a bright smile.
"Of course."
Seeing her determination, he couldn't help but feel genuinely happy.