That afternoon, I headed to the research institute alone.
It was a routine progress check.
The report had been submitted, but it was still best to see things in person.
Just past the entrance, the Director in a white lab coat was waiting.
She bowed deeply.
"Your Majesty the Demon King, welcome! I have been eagerly awaiting your arrival!"
"Thank you for your hard work. Sorry to bother you during such a busy time."
When I said that, the Director waved her hand dismissively.
"Not at all, not at all! I owe the Demon King a tremendous debt, so please let me help with something like this. Besides, now that I've been given this body, I can manage without sleep or rest!"
The Director puffed out her chest proudly.
Her legs, from the knees down, were translucent.
Her form was vague, and her skin had a faint bluish pallor.
This went beyond merely looking unhealthy.
As her appearance made clear, the Director had abandoned humanity.
She had transformed into a phantom.
Among undead, phantoms belonged to the spiritual category, and their racial strength ranked from mid to high.
Some individuals could even command numerous spiritual bodies to create territories.
Even alone, they possessed considerable strength.
In truth, this was not the result I had intended.
My original plan had been to turn her into a special ghost with self-awareness.
Both were spiritual entities, but ghosts were far more common.
They weren't particularly powerful, but that was irrelevant for someone in research.
The ease and reliability of the transformation was also a plus.
By discarding a physical body, fatigue and sleep became a thing of the past.
Partial materialization was also possible, so it wouldn't interfere with research.
It was truly the ideal race.
And so I cast the ghostification spell on the Director.
The spell succeeded without a hitch.
Yet somehow, she ended up transforming into a phantom.
It was no mistake on my part.
I checked many times afterward, and the spell hadn't failed.
Despite that, the result was different from what I had anticipated.
After considering various possibilities, I arrived at a hypothesis.
The conclusion I reached was that the Director's mentality was the cause.
Her obsession with research had elevated her existence as an undead.
Strong thoughts exert a powerful influence on magic.
For a spiritual being that had discarded its fleshly body, this effect was even more pronounced.
No other cause could be considered.
I had long been amazed by her researcher's temperament, but I never expected it to go this far.
In any case, transforming into a phantom was not a bad thing.
Racially, it ranked quite high.
There were no particular disadvantages compared to a ghost.
"Has becoming non-human caused any inconveniences?"
"None at all, actually! I can't eat or sleep anymore, but I always found those to be nothing but nuisances. Since gaining this form, my work efficiency has skyrocketed, and I no longer get injured in lab accidents. It's nothing but good things!"
The Director, floating at low altitude, wandered around while chattering away at full speed.
At that moment, a beam of sunlight near the entrance grazed her.
Screaming, the Director tumbled dramatically and vanished into the depths of the institute.
Other staff members watched the spectacle with expressions of weary resignation.
(Being a spiritual-type undead, she apparently can't stand sunlight.)
That said, as a phantom, she wouldn't be destroyed instantly.
There was no life-threatening impact, so there was no need to worry.
The Director had seemed to dislike sunlight ever since she was human.
She had always hated going out, lamenting that she wanted to stay cooped up indoors.
In that sense, I thought her current state wasn't so different.
With a touch of exasperation, I entered the institute.
Having recovered from the direct sunlight, the Director immediately moved ahead of me.
She asked me.
"By the way, you've come to check on that thing again today, haven't you?"
I understood her question.
There was nothing to hide, so I nodded.
"That's right. Nothing problematic has come up, has it?"
"No, everything is fine! We're keeping a close watch on it. If anything abnormal occurs, the alarm will activate immediately."
The Director wore a fearless smile.
In a self-satisfied manner, she adjusted her glasses with a finger.
Glasses were supposed to be unnecessary for her now, but the Director still wore them for some reason.
The same went for the lab coat.
Perhaps it was the Director's own personal quirk.
We descended to the fifth basement level of the research institute.
It was a newly constructed area, established within the last six months.
The facility had been steadily expanding, with additional surface floors and separate wings being added.
It had become the premier facility in the entire Royal Capital.
It was growing at a pace that might one day surpass even the Demon King's castle.
The Director unlocked multiple layers of security and proceeded inward.
I followed behind her.
Eventually, the final door was opened.
In the center of a modestly sized room, a secured glass container was installed.
The Director stopped at the entrance.
"Please, go ahead and verify."
I nodded, stepped inside, and peered into the glass container.
Sealed within multiple layers of barriers, a black, water-like substance floated.
The black substance writhed irregularly inside the container.
This was the soul of Balk, former Commander of the Four Heavenly Kings.
I had killed him when he was secretly trying to resurrect himself.
The destroyed soul had begun repairing itself once again.
That was why I had gathered it up and sealed it away.
It had taken considerable effort, but I certainly couldn't just leave it be.
Currently, by constantly destroying the soul, I was both preventing its repair and accelerating the collapse of its ego.
Balk, sealed within the container, had become something like residual thoughts.
He probably couldn't think at all anymore.
Even so, Balk's tenacity was astonishing.
He had been trying to overcome death twice by his own power.
If I hadn't intervened, he would have achieved resurrection within a few years.
He was unquestionably a superhuman.
He lived only for revenge against me and the revival of the Demon King's army.
That iron will was something I couldn't help but find terrifying.
This room constantly monitored Balk's soul.
While keeping watch, it also analyzed the mechanisms of soul restoration.
The goal was to produce a resurrection technique of an entirely new type.
Revival from a state of soul destruction was a truly extraordinary feat.
If we could reproduce it, it could be applied in various scenarios.
It was supposed to breathe new life into stalled research.
Having finished my observation, I left the room.
The Director locked the door and asked me.
"Are you finished?"
"Yes, the check is complete. That's enough."
We retraced our steps.
On the way back, the Director began talking at length.
"The soul restoration technique still doesn't seem ready for systematization... There are aptitude issues, and the analysis is still somewhat lacking. It feels like it's tied to the soul's innate abilities."
"It sounds like you're struggling, but you seem pleased."
"Absolutely! That's what makes it worth researching! I get so excited about it. If I were still human, I would have died of overwork long ago!"
The Director gave a thumbs-up with a beaming smile.
In her case, it was no joke.
There had been a time when she truly was on the brink of death from overwork.
The fact that she had been completely absorbed in her research even in that state made me glad once more that she had become an undead.
The Director remained cheerful for a while, but then noticed something and made an embarrassed face.
She hurriedly bowed to me.
"Ah, but from the Demon King's perspective, delays in analysis are unacceptable, aren't they? I'm sorry!"
"No, it's fine. I understand how difficult it is. Take your time and proceed as you see fit. I'll leave those decisions to you."
When I told her that, the Director froze.
She suddenly began to tremble all over.
"Ah, a-a-a, ah..."
The Director let out disjointed, delirious murmurs.
She was clearly not in her right mind.
As I watched her sudden strange behavior with puzzlement, the Director suddenly prostrated herself before me.
Pressing her head to the floor, she raised her voice.
"Thank you so much! I'm truly, genuinely happy! I will give it my all, with complete sincerity, as if my life depends on it! Yes!"
"...Very well."
Too stunned to respond, I couldn't find anything witty to say.