The next day, contact came from the research institute.
They had identified the substance contained within the magical beasts.
To state the conclusion first, the drug was crafted from materials harvestable from the former Demon Territory, possessing the efficacy to forcibly mutate living creatures.
The results were largely as anticipated.
The humans from the Republic must have ventured into the former Demon Territory to procure the drug's raw materials.
Their targets were likely the water and plants steeped in high concentrations of miasma.
Given years of research, it would not be surprising if they could produce a drug like this one.
From an ethical standpoint, of course, it was a major issue.
While illegal potions were numerous, a substance with this kind of efficacy was unprecedented.
The series of magical beast incidents had occurred because the drug had been administered to humans who were present in cities outside the country.
The manifestation of its effects seemed to occur with a time lag, making it undetectable until it fully activated.
Their countermeasures against detection in that regard appeared to have been thorough.
The drug's creator likely had some knowledge of magic.
(To be able to create magical beasts everywhere without anyone noticing...)
Though it was not my place to speak, as one who transforms the living into undead to control them, this was undoubtedly inhumane.
The world should not have become one where such acts could be easily carried out.
I would stop this early on.
The research institute had designated the drug in question as a "magical beast drug" and planned to conduct further analysis.
Currently, they were attempting to develop a treatment.
Whether they would succeed was uncertain, but it was likely a matter worth pursuing.
It's an unlikely scenario, but there is a risk that my subordinates could be drugged.
When that happens, I can't afford to simply throw up my hands in despair.
Now that I understand the cause, I need to establish countermeasures immediately.
(Developing a cure is important, but we must also advance toward a fundamental solution.)
If we continue to play catch-up like this, the harm will only increase.
I want to capture the mastermind as soon as possible, but I still haven't identified their whereabouts.
Even so, there were actions I could take.
The simplest would be to destroy the Old Demon Territory where the raw materials for the bestialization drugs are harvested.
The raw materials cannot be cultivated so easily.
They are born from the magical power and miasma of the Old Demon Territory.
Replicating that environment elsewhere would be an extraordinarily difficult task, and not very practical.
Therefore, when producing the drugs, the Republic's agents must travel to the Old Demon Territory.
That is where they gather the raw materials.
If they can no longer obtain the materials from the Old Demon Territory, they will be forced to produce the drugs using only their current stock.
The production speed will plummet drastically, causing significant delays in their plans.
During that time, I intended to find the mastermind.
Once I determine who is pulling the strings, I can eliminate just that individual.
In terms of pure combat ability, there are very few who surpass me.
Unless it's an out-of-the-ordinary existence like a Great Spirit, I wouldn't expect a difficult fight.
If I can only locate my target, a swift resolution can be expected.
All that remained was to retrieve the stored magical beast medicine and capture those who had been administered it; then this turmoil could be brought to an end.
At that moment, the door to the audience chamber opened.
The one who appeared was Grom.
He did not seem particularly flustered, nor did he give off the atmosphere of someone arriving to make a report.
I addressed Grom.
"What is it?"
"No, I was merely wondering if there was anything I might assist with, and so I came to seek an audience with the Maou, Your Excellency."
Grom spoke, his gaze fixed appraisingly upon me.
Currently, the Demon King's army could not be mobilized, but he likely wished to contribute in his own way.
He must have been feeling restless, unable to sit idle, and so he had come directly to me to receive orders.
"I see. I appreciate your concern."
I offered my thanks sincerely.
Grom remained, as ever, a loyal retainer.
I did not want to dismiss his initiative here.
I had been planning to depart for the former Demonkin territory, but since he was here, perhaps we could cooperate on the task.
With that thought, I made a suggestion to him.
"It isn't exactly work, but there is something I could use a little help with. Could I ask it of you?"
"Of course! This Grom, for the sake of the Maou, would leap straight into hellfire!"
Grom answered with spirited enthusiasm.
Even if he did leap into hellfire, it would cause no physical harm to him whatsoever.
He would stroll through the flames if he had to.
But that was a promise of his loyalty.
To nitpick would be tasteless.
◆
Grom and I teleported from the royal castle.
Our destination was the dark wasteland of the former Demonkin Territory.
Grom scanned our surroundings.
"This place is..."
"The former Demonkin Territory. This is where we must begin."
"What, specifically, will you do?"
At Grom's question, I gave the prepared answer.
"Purify the atmosphere, and utterly devastate the land. I intend to ensure it can never produce raw materials again."
It was something I had considered even at the castle, and a priority measure to counter the magical beast drugs.
If I turned this into a barren wasteland where nothing could grow, producing new magical beast drugs would become difficult.
At the very least, mass production would be impossible for the immediate future.
Grom rubbed his chin and spoke with an impressed tone.
"Oh my... that is quite bold. As expected of the Demon Lord."
While Grom was praising me, his subtle movements were unnatural.
He was exhibiting behavior as if searching for something.
Most likely, he was trying to acclimate to the air of the former Demonkin Territory.
This land is quite peculiar.
For humans, it would cause bodily harm.
For Grom, a top-tier undead, it was a suitable environment, but even he required a certain degree of acclimation.
Once Grom had settled, I gave him an instruction.
"Try absorbing the miasma in this area as a test."
"Understood!"
Grom nodded and extended his eight arms.
Standing like a statue, he fell still and began concentrating his awareness.
The magical power and miasma in the air started to be drawn into his body.
Soon, Grom collapsed to one knee, groaning in pain.
"Urgh... This... is... quite the ordeal, I see..."
Miasma that isn't one's own naturally provokes a kind of rejection response.
The sense of foreign intrusion comes with immense agony.
It must feel like being torn apart from within.
Left unchecked, it could even erode the soul.
I had once done the same thing in the Valley of the Dead.
That's why I understand Grom's suffering well.
"It will become easier to bear as you acclimate. Just endure it for now."
"My Lord Demon King...! GRRRAAAGH! THIS... IS NOTHING... AT ALL!"
Grom roared as he forced himself to stand.
The absorption had suddenly stabilized.
The miasma in the surroundings thinned away, and before long it vanished entirely.
Only the miasma in this immediate area had been hollowed out into nothing.
Grom had drained every last trace of it.
"Hmm, it seems to have worked."
"Hah... hah... hah..."
Grom was panting heavily.
He was thoroughly exhausted.
He was a skeleton—he shouldn't have been able to breathe in the first place, and yet he was gasping for air all the same.
No one knew why.
"Are you alright?"
"O-Of course... I-I still have plenty... left in me..."
"Take some rest first. I'd like you to absorb the miasma from other locations as well. I'll be traveling to various sites to purify them myself."
"Understood..."
Grom sank down into a seated position.
It would take some time before he could function again.
I left him behind and teleported away.
After that, I swept through the old demon territory, siphoning away every trace of miasma and mana left within it.
The handful of demons still lingering were slaughtered, and I followed up by razing the land with barrages of forbidden spells.
From partway through, Grom rejoined the effort, and the speed of destruction increased dramatically.
And so we turned the old demon territory into a true wasteland.