The following day, I traveled to a sprawling expanse of land on the outskirts of the Royal Capital.
Carved out of a grassy plain, the area's reddish-brown soil lay bare and exposed. Craters pockmarked the ground here and there, and prominent scorch marks were scattered among the debris. A wooden structure loomed in the distance.
This was the Demon King's Army Dedicated Training Ground.
The capital's existing facilities had grown too cramped as our numbers swelled, so I had established this new site at Henry's request. Here, training under conditions mimicking actual combat was possible, and various terrains could be replicated using magic. Because the area was encased in a barrier, there was no need to worry about collateral damage to the surrounding region. The soundproofing was equally flawless, ensuring we remained good neighbors to the local environment.
"Oho, quite impressive. It is no wonder your soldiers are so well-trained."
The one raising her voice in admiration beside me was the preceding Demon King, Diera. She was unusually high-spirited. Having spent the entire night clashing with Grom, she seemed thoroughly satisfied in both body and spirit. Diera was a battle maniac, no less so than Henry. She surveyed the area with wide-eyed curiosity.
Prompted by a sudden thought, I asked her a question. "In your era, did you never think to build a facility like this?"
"I was in no position to focus on the upbringing of subordinates. Had you gone a little easier on me, I might have had the leisure to do so, however."
She shot me a sideways glance, her words tinged with a faint note of reproach.
"...I won't apologize."
"Of course not. You had your duty. I have no intention of harping on the past now."
Diera shrugged and laughed. Apparently, the jab was merely a light joke. She did not dwell on the past; she seemed to be genuinely enjoying her new life. While she occasionally dug up old grievances like this, she wasn't serious. If anything, she seemed to enjoy my reaction. I had no way of knowing it back then, but it seemed this was simply Diera’s personality.
"Even so, if you possess this much architectural skill, you could at least build a house for me, could you not?"
"Manage on your own. I have already provided the materials," I replied instantly.
Currently, Diera was living in the Former Demon Territory. That land, once contaminated by miasma, had been cleansed by the destruction caused by my forbidden magic. Now, its environment was little different from any other land on the continent. She lived a modest life there, refusing to officially join the Demon King’s Army and insisting on remaining a mere neighbor. It was a matter of principle for her, it seemed.
That said, she clearly felt the inconveniences of daily life quite often. The fact that she was a frequent visitor to the Demon King's Domain was proof enough of that.
"Nuu, how cold... If a certain Sage hadn't seen fit to detonate my castle, I would still have a roof over my head."
Diera stared at me out of the corner of her eye once more. She was referring to the time I had used Great Magic to level her fortress. That had been the result of choosing the most efficient course of action at the time. I never imagined I would be listening to the Demon King herself complain about it a decade later.
As we exchanged such banter, the Demon King's Army began to line up in the distance. They formed ranks with swift, practiced movements and launched an attack toward a target. The thunderous echoes of countless gunshots filled the air. Seeing this, Diera narrowed her eyes to observe more closely.
"They look like staves, but what exactly are those weapons?"
"It's a gun. It fires lead bullets at the enemy. You could call it an evolution of the bow."
The guns captured in the Technomagic Kingdom had undergone further improvements, evolving into our own unique weaponry. The rate of fire and accuracy had improved to a level where they were fully viable for practical combat. Mass production had already begun. Within the Demon King's Army, specialized units had already been formed.
Diera studied the gun training carefully. She stroked her chin as she offered her opinion. "Looking at that, it is likely for anti-personnel use. Mages would likely despise such a thing."
Her assessment was correct. Guns would likely become the ultimate mage slayer weapon in future wars. In addition to being able to perform accurate attacks from a distance without the need for chanting, they did not require the years of training that a bow did. As long as one mastered the basic operations, anyone could use them. A weapon with such high versatility was a rare find.
Behind the gun unit, even newer weapons made an appearance. Diera furrowed her brows and tilted her head. "That is... an iron carriage?"
"It is a weapon called a tank. It destroys targets from long range using beams of magic power. Ordinary magic can neither block nor evade it," I explained.
That was another weapon captured from the Technomagic Kingdom. Its defining feature was the powerful beam fired from its main cannon. We hadn't produced many yet, but I intended to form a full unit with them eventually.
"To think you would develop such a ferocious weapon... the Sage's wisdom is as sharp as ever."
"I did not come up with it. I merely repurposed what modern technicians had devised."
Both inventions were based on the flashes of inspiration from John Doe. His talent would have undoubtedly caused human civilization to leap forward. Even though there were unavoidable reasons for my actions, I had snuffed out the potential of his genius. I harbored no regrets, but it was a fact I did not intend to forget.
Diera watched the maneuvers for a while longer before turning back to me. She posed a pointed question. "Why have you shown me these things now?"
"As part of the sightseeing. They have finally taken shape, so I wanted to showcase them."
Diera and I shared the commonality of being Demon Kings. We were once archenemies, but now we were something like a senior and a junior in the trade. Her opinion was valuable. While the pretext of sightseeing wasn't a lie, my true desire was to learn of any points for improvement from the perspective of a former Demon King.
The Demon King's Army was still a work in progress. I wanted to strive for further strengthening by reflecting any feedback she might have. Diera, who likely saw right through me, let out an exasperated laugh.
"You truly are fastidious... By the way, can I operate that as well?"
She pointed toward a tank. I had noticed her paying an unusual amount of attention to it for a while now; it seemed she was fascinated. She looked quite restless, her usual composure replaced by an itch for action.
"Operating it is possible. Would you like to try it out?"
"Oh! I should very much like that!"
Diera raised both hands in joy. It was a reaction like that of a child—completely innocent. Looking at her now, one could hardly associate her with the former Demon King.
We moved toward the soldiers currently in training. The subordinates were astonished to see us, yet they didn't break their form. Suppressing their agitation, they continued their assault on the mock enemies. Henry broke away from the group and approached us.
"Hey, Boss. What brings you here today?"
"Diera says she wants to try using the weaponry. I'd like you to show her the ropes."
"Ah, sure thing. Leave it to me."
Henry immediately agreed. On the other hand, Diera made a sudden, slightly anxious confession. "I only know how to handle a spear; is that quite all right?"
"Anyone can handle the basic operations," Henry replied in a cheerful tone. He gestured for Diera to follow him and headed toward the nearest tank.
As I watched them go, Diera looked back at me and shouted, "Dwight! Why are you just standing there? You're coming too!"
"...I'll pass."
"What kind of Demon King is so passive! Archer, do you not think so too?"
Diera shouted as if my refusal was beyond belief. To make matters worse, she even started dragging Henry into it. Henry placed his hand on his hip and thought for a moment before revealing a ferocious smile.
"True enough. I feel bad for the Boss after his all-nighter, but let’s play a bit, shall we? I’ve been wanting to have a gunfight too."
"...Understood."
Seeing their expectant gazes, I nodded reluctantly. I had intended to watch quietly from the sidelines, but it couldn't be helped. I was the one who decided to bring her here. I suppose I can go along with their whims for a little while.