"Whew…"
The long-haired brunette, a high school student, exhaled weakly as she collapsed onto the couch.
The magical book in her hands slipped to the floor, and her legs—bare now, the black stockings discarded—gleamed softly under the warm lamplight.
Across from her, Kai sat with a cup of tea in hand, watching her with an amused smile.
"By the way, you shouldn't push yourself so hard when you're first learning magic. You've completely drained your mana, haven't you?"
His tone was light, but deep down, Kai was genuinely impressed by Utaha Kasumigaoka's talent.
In just a few hours, she had grasped the fundamentals of magic and had become a properly qualified low-ranked demon.
"How was I supposed to know it would end like this? And you didn't even bother to warn me," Utaha muttered, rolling her eyes as she slowly sat up. "By the way, my perverted master, your servant's over here looking like death, and all you can do is stare at her legs. Care to do something useful?"
"If you insist, I can replenish your mana," Kai offered, sipping his tea.
"Replenish my mana? As in, restore my magical energy?" Utaha's eyes lit up. "If that's possible, then do it. Now!"
"You said it," Kai replied with a smirk.
Utaha, desperate to regain her strength, leaned forward eagerly—until she noticed something odd.
Kai's crimson eyes were drawing closer… far too close.
Uh…?
Why was he getting this close just to transfer mana?
She was about to ask—
But his lips were already on hers.
Utaha's eyes flew wide open in shock.
This was mana replenishment?!
...
Silence fell over the room.
The only sound was the subtle hum of magical energy circulating between their bodies.
"You planned this from the start, didn't you, you perverted master?" Utaha muttered, curling her legs under her, face flushed red.
"I am replenishing your mana. This is hard work, I'll have you know," Kai said, feigning a wounded expression.
Utaha shot him a look full of disbelief, her hands slowly curling into tiny fists.
So I'm the one taking advantage of him now, huh?
How annoying.
Kai casually pulled out his phone. "Next time, be more careful not to completely drain your mana. I've sent you the documents—get your transfer to my school sorted."
Utaha exhaled deeply and squinted at him. "Demons go to school?"
"Obviously. Can't you see my uniform?"
"I just assumed it was some weird fetish thing of my perverted master's."
"Keep the summoning flyer I gave you. If you're ever in danger, use it to call me right away."
Despite her sass, Kai decided to take the time to explain the basics to her.
Utaha was clearly gifted and had already become a low-ranked demon, but she was still a total novice when it came to the world of mysticism. A bit of guidance wouldn't hurt.
"Fine. I'll be careful," she replied, her tone shifting to something more serious. "I'll transfer schools as soon as I can."
Kai nodded. "Good."
The next moment, a glowing teleportation circle lit up beneath his feet.
Teleportation magic—it was common enough among demons. Once a circle was set up, it allowed for instantaneous travel.
But "common" didn't mean "easy."
Kai had poured a lot of effort into mastering it.
Whoosh!
A burst of golden light, and Kai's figure vanished.
He reappeared in his apartment.
He lived alone.
Not that he had neighbors—he owned the whole building.
It was late at night.
But sleep wasn't on his agenda. He pulled out a new stack of magical tomes.
Rias had left behind quite the collection. No sense wasting time.
For demons, going days without sleep wasn't a problem.
...
Days passed in a flash.
Now—
Inside his apartment.
Kai was sprawled across the couch, eyes half-closed, seemingly dozing.
But inside, profound changes were taking place.
His already formidable magical energy surged like a tidal wave, intensifying by the second.
No one knew how much time had passed before Kai finally exhaled a murky breath and summoned his virtual interface.
---
[Kai]
[Class: Origin Mage]
[Magic: Origin Lightning Magic LV10 (+)]
[Origin Points: 10]
---
"Each upgrade to Origin Magic costs more and more Origin Points," Kai muttered as he studied the panel.
He hadn't stepped outside in days.
As for school, he simply let Rias know, and everything was taken care of.
Aside from a few calls from Utaha reporting her transfer status, no one had disturbed him.
He'd buried himself in those magic books, reading through all of Rias's collection. The payoff? A mountain of Origin Points.
And he'd invested every last one into Origin Magic.
Compared to regular magic, Origin Magic required a ridiculous amount of resources to enhance.
Even with all the points he had, he'd only just managed to push it to Level 10.
Still—the transformation was worth it.
His power had undergone a complete metamorphosis.
Even Kai himself wasn't entirely sure what his current rank was.
Judging by the intensity of his mana, he had likely just broken into the realm of High-Class Demons.
But with Origin Magic in play… his actual combat strength was impossible to gauge.
"I wonder… can I go toe-to-toe with the monsters among the High-Class Demons now?"
Once you reached the High-Class level, the power gap between individuals became astronomical.
At that tier, one wrong move could still get you instantly annihilated.
After all, raw magical energy was just one factor.
Sacred Artifacts—especially the Longinus-class weapons—could skyrocket a demon's battle capabilities.
"But Origin Magic… it really lives up to its name."
Kai clenched his fist, a quiet grin tugging at his lips.
Before, he had been a classic "glass cannon."
Now, his growth had become comprehensive.
Not just magical power—his body, his senses, even his instincts had evolved beyond the norm.
"Hm?"
His expression darkened. He stepped toward the window.
Just now, he'd sensed a burst of Holy energy.
This was Kuoh City—demon territory.
Anyone using Holy power here had no business doing so.
Without hesitation, Kai extended his perception outward.
A moment later, his eyes turned cold.
"Looking to die, are you?"
A terrifying bloodlust surged from his body, causing the air to shudder.
Someone was attacking one of Rias's servants.
In the next instant—
Golden lightning erupted around Kai's body.
He became a streak of light—
—and vanished beyond the horizon.