Chapter 28 — Construction Technique: Reforged
"What?"
"The matter created by Construction Technique may be real," Ren continued calmly, "but it isn't eternal, is it?"
"Anything that truly exists is subject to wear and decay. Water evaporates. Food spoils. Metal rusts. That impermanence is part of what makes it real—and it's also the prerequisite for forming a binding vow."
He spoke with steady confidence.
"Let water evaporate ten thousand times faster—in exchange for constructing water ten thousand times more efficiently.
Let metal corrode ten thousand times faster—in exchange for constructing metal more efficiently."
"After all, we don't need what you create to last forever."
He looked her in the eye.
"We only need the bullet to exist for the fraction of a second before it pierces the enemy's brain."
Mai hesitated. "C-can something like that really work?"
"Let's test it."
Then he added thoughtfully, "To avoid accidents, start with a temporary binding vow. Restrict it to just the next activation of Construction Technique. The effect might be weaker, but this is only to confirm whether the theory is viable."
She nodded.
Closing her eyes, she steadied her breathing and silently forged the vow within her mind.
A constraint.
A price.
A trade.
Then—
She formed the hand seals.
Cursed energy gathered at her fingertips.
Construction activated.
A flash of white light flickered—
And a brass bullet materialized cleanly in her grasp.
Her eyes snapped open.
"I-it worked!"
Her voice trembled—not from exhaustion this time, but from disbelief.
The cursed energy drain was there… but it was manageable.
Not crushing. Not fatal.
For the first time, Construction Technique didn't feel like a noose tightening around her throat.
It felt… usable.
She stared at the bullet that had materialized out of thin air in her palm, excitement practically spilling out of her.
Closing her eyes again, she carefully felt the flow of her cursed energy.
It was… negligible.
When she opened them, her voice trembled with exhilaration.
"I think… I could make ten thousand of these!"
Just days ago, creating a second bullet in a single day had nearly killed her.
Now, ten thousand didn't even feel out of reach.
The sheer leap in power felt like a personal Big Bang.
"Ren, you're amazing!"
She lunged forward and threw her arms around him, pressing her lips against his in a flurry of chaotic kisses.
"Mmh—wait—"
Ren, ambushed, flushed bright red. He struggled weakly at first, arms flailing… then slowly gave up, letting them fall as she continued her enthusiastic assault.
Only after a long while did they finally part.
Mai's green amber eyes shimmered, still blazing with excitement. Before stepping back fully, she leaned in and pecked his lips once more.
"Now I don't have to worry about being left behind by you," she said happily. "I can finally—barely—keep up with your pace."
Ren blinked.
"Wait… the person you were trying to catch up to… was me?"
So he was the indirect cause of her overexertion? The reason she'd pushed herself into collapse?
"Well… not entirely…" Mai faltered, cheeks tinged pink. She wasn't about to admit too much in front of the person she liked. "There are other reasons."
"Like who?" he pressed curiously.
"That's none of your business!" she shot back, turning her head. The usually sharp-tongued, domineering girl rarely looked this flustered.
Which, admittedly, suited her.
Just as Ren prepared to pry further, she abruptly changed the subject.
"Anyway! With this upgrade, I need to rethink how I use my technique."
Her earlier shyness vanished instantly. She puffed up with renewed swagger.
"Forget pretending I only have six bullets when I secretly have seven. That's pathetic!"
"Now I have ten thousand!"
She mimed holding a gun, eyes gleaming.
"So maybe it's time to switch weapons. Submachine gun? Heavy machine gun? Three thousand six hundred rounds per minute—ratatatata! Just shred cursed spirits into confetti!"
"…"
Ren couldn't help laughing.
"What?" she demanded.
He reached out and flicked her forehead.
"Your immediate priority," he said dryly, "isn't building bullets at Jujutsu High. It's enrolling in a university and studying high-energy physics and polymer materials."
Mai stared blankly. "Huh?"
"The essence of Construction Technique," he explained, "is materials."
Over the past few days, he'd come to understand this clearly.
A Construction sorcerer was like a craftsman. The strength of what they built depended entirely on the properties of the base materials they understood.
Which meant—
The technique's true power was limited by the user's knowledge. More fundamentally, by the scientific level of their era.
A Stone Age sorcerer couldn't imagine constructing steel.
A Heian-era sorcerer couldn't conceptualize bullets.
A Sengoku-era sorcerer couldn't dream of planes or tanks.
Even a Meiji-era sorcerer…
In short—
In the modern world, where physics, chemistry, and biology evolve at breakneck speed, Construction Technique was no longer shackled by history.
If properly optimized, this era might very well belong to it.
"Listen carefully," Ren added seriously. "The binding vow you formed doesn't directly reduce cursed energy consumption. It increases your cursed energy control precision. You understand that, right?"
Mai nodded.
In the jujutsu world, efficiency and precision were inseparable. The finer one's cursed energy manipulation, the less waste in technique execution.
And that was precisely why he'd designed the vow that way.
Modern scientific breakthroughs largely occurred at microscopic scales. By increasing her control precision, she could construct matter at finer structural levels.
Meaning—
Her Construction Technique could merge with modern science.
It wasn't just lowering energy cost. It was killing two birds with one stone.
If she could reach molecular-level construction… or even atomic-level—
Her potential would be terrifying.
"Still," Mai groaned, tongue slightly out in complaint, "what the heck is 'high-energy psyche' and 'polymer materials'? It already sounds like a headache."
"It's high-energy physics," he corrected. "You're still in Jujutsu High. You'll understand when you get to university."
"And what if I can't handle it?"
"You have to. Even if it kills you, you study."
He said it through gritted teeth.
And in that moment, he suddenly understood the mentality of those overbearing parents from his previous life who pushed their children mercilessly.
Because sometimes—
Relentless effort wasn't about ambition.
It was about survival.