Chapter 77 — Domain Compatibility
"…What?!"
The moment Yuki Tsukumo slightly lifted her hand—
Ren reacted instantly.
He lunged forward and clung to her like an octopus, wrapping himself around her with desperate force—just short of growing suction cups.
Feeling the sheer intensity of his grip, Yuki smiled.
"That's more like it," she said, gently patting his head, her expression full of amusement. "Why do you act so distant from your master?"
"You should learn to rely on me more, you know?"
She pressed a hand to the back of his head and even rubbed her cheek lightly against his smooth face, laughing softly.
This is not 'relying' on you at all!
Ren broke out in cold sweat.
This is life-threatening coercion! This is basically attempted murder!
Ignoring his resentful glare, Yuki dismissed her domain.
In an instant, the world returned to normal—the bright sunlight, green trees, and open training field reappeared.
She stretched lazily, rolling her shoulders.
"Well then, that's it. Go back and figure things out on your own."
"…That's it?" Ren asked, baffled, after jumping off her.
"What else?" Yuki replied casually.
"I can't pinpoint what's wrong with you right now."
"But after experiencing a domain firsthand, you should've gained some new insights, right?"
"Take those ideas and work on them. Maybe this time, you'll get it right."
Ren stared at her bright, carefree smile, momentarily speechless.
This woman… not only lives lazily—she teaches the same way too…
Still—
she wasn't wrong.
After experiencing Domain Expansion personally, aside from the sheer shock—
he had gained a number of insights.
"Work on it for a few days first," Yuki said, patting his shoulder.
"If you want to experience a domain again, have questions, or just miss your master—come find me anytime."
"Though for domain demonstrations—once per day only. You know that, right?"
"I do." Ren nodded.
—
Domain Expansion was a "guaranteed-hit, guaranteed-kill" technique—immensely powerful, but heavily restricted.
Because of its extreme energy consumption, it could generally only be used once per day.
After activation, the user would enter a state of technique burnout, temporarily unable to use their cursed technique.
That meant—
choosing when to use it was critical.
It was a trump card that couldn't be revealed lightly.
But for Ren…
that was still far off.
Right now, his biggest problem was simple:
How do I even achieve Domain Expansion?
"In the meantime," Yuki added, resting her chin on her hand, "I'll also think more about your situation."
"If you can solve it yourself, great."
"If not, we'll figure it out together later."
"Got it."
"Ren! Yuki-senpai!"
In the distance, Utahime came running toward them, slightly out of breath.
On the way back, Ren replayed everything that had just happened.
The sudden appearance of a mysterious woman.
Beating him up.
Then deciding to teach him Domain Expansion.
Taking him as her disciple.
And even showing him a complete Domain Expansion firsthand.
That image lingered in his mind—
A tall, golden-haired woman leaning casually against a motorcycle—
Confident. Wild. Unrestrained.
Yet somehow—
effortlessly free.
Ren had a strong intuition—
this so-called "idle" woman was definitely not the type to obediently follow orders.
So then—
why would someone like her, who lived freely overseas, willingly return all this way just to teach him Domain Expansion?
"Utahime-sensei," Ren suddenly asked, turning toward Utahime Iori, "did you have to go through a lot of trouble to invite Ms. Yuki Tsukumo back for me?"
"W-well… it wasn't that bad," Utahime replied, suddenly looking a bit awkward.
She lowered her head, brushing a strand of hair by her cheek. At the same time, a faint blush crept onto her face.
"…Honestly, I didn't really do much."
"I just told her that a first-year beat her prized student, Aoi Todo, so badly he couldn't even get out of bed."
"…What?"
"Oh—so it was you?!"
In an instant, Ren recalled that sunset and the burning pain of that kick to his backside.
He had been furious… yet completely unable to protest.
Still—
Yuki's Domain Expansion had indeed given him valuable inspiration.
He spent several more days immersed in focused practice.
But—
nothing changed.
Just like before—
the moment he injected his innate domain, the barrier he painstakingly constructed collapsed instantly, crumbling into nothing.
Not even a fraction of a second longer than before.
"What the hell is going on…?"
Sitting in the classroom, Ren let out a long sigh, tilting his head back in frustration.
"I feel like I've already done everything right…"
Across from him, Yuki wore an equally serious expression.
After a moment of thought, she spoke slowly:
"Is it possible…"
"…that your technique simply isn't suited for Domain Expansion?"
"…What?!"
Ren's eyes widened in shock.
Even Utahime stared at Yuki in disbelief.
"That's… a thing?"
"It's not impossible," Yuki said, resting her chin on her hand, calmly analyzing.
"There's something called compatibility between a sorcerer's technique and their domain."
"For example—an ancient sorcerer named Dhruv. His technique inherently contained a domain. The trajectory of his shikigami could directly manifest into one."
"And then there's Kinji Hakari from Tokyo Jujutsu High. His domain is also derived directly from his technique."
"They don't need to study barrier techniques at all."
"They can expand domains purely through the nature of their techniques."
"If techniques with excellent compatibility exist—"
"then theoretically…"
"…there must also be techniques with poor compatibility."
"…That…"
Ren had to admit—it made sense.
But—
he didn't want to accept it.
"Then…" he looked at Yuki, his expression filled with despair, "does that mean I can't use Domain Expansion at all… Master?"
Domain Expansion—
was the dividing line.
The absolute boundary between top-tier sorcerers and everyone else.
A wall that could not be crossed.
Ren could not—
would not—
accept being unable to use it.
"It's not that absolute," Yuki said, her golden eyes shifting as a faint smile curved her lips.
"What I mentioned is only about good or bad compatibility—not a final verdict."
"Techniques with good compatibility can achieve Domain Expansion more easily."
"Those with poor compatibility…"
"…might just need more effort."
"And besides—"
Her eyes narrowed slightly.
"I think…"
"…I may have already figured out why you can't expand your domain."