Sinking the tower into the sea had its advantages and disadvantages. The advantage was that it would be hidden from everyone's eyes, drastically reducing the likelihood of an attack.

'The disadvantage...'

Activity outside would become almost impossible. The tower was sturdy enough to withstand the deep sea, but the monsters could hardly breathe underwater.

'I'll leave the Poil Orcs where they are.'

Confining orcs to the tower when they needed to run through snowy mountains and follow their instincts was hardly a good choice. Why bother when, left to themselves, they would expand their influence and build an army?

'Of course, first I'll take as many Poil Orcs as possible as servants, so they won't feel abandoned now that I can no longer stay nearby to help.'

He had already told Krutu to bring his finest warriors. It would cost a little more demonic energy, but his accumulated notoriety was supplying enormous amounts of it by the moment.

'But the legs will hold up underwater, won't they?'

The dwarves said there would be no problem. Berge, too, doubted that the legs, strengthened by the tower, would cause any serious trouble. Still, nothing was certain. No one had ever put a tower underwater before.

"The tower is going into the sea?"

"To think I'll witness this enormous thing walking through the deep sea! I could die without regrets."

"What do you mean, without regrets? Once a golem can rise from lying down, you want it to walk; once it walks, you want it to run; once it runs, you want it to fly!"

"Exactly. Are we stopping here? We've created a masterpiece, but we can make it even greater!"

"First, we'll have to check whether it can withstand the sea. This will provide some quite valuable data."

"Fascinating."

Berge could only marvel at the dwarves' collective ingenuity—and their madness—as they volunteered to repair the legs if anything went wrong.

'Running and flying?'

Running seemed plausible. Honestly, he thought it would be possible immediately if he poured enough demonic energy points into it.

But flying through the sky?

'A sky tower?'

It was an intriguing idea. Intriguing enough that it might be worth making one someday, if the opportunity arose.

Otherwise, no one opposed sinking the tower into the sea. Well, the more recently abducted princesses protested, but the dwarven princess quieted them down. Those things had no say in the first place.

'Clearly, not every princess is unusual.'

Ernyan, Kaede, Elena, Lavinia, and Louise. They were exceptionally talented and exceptionally special—no, peculiar.

The other five princesses were nowhere near as valuable. It was enough for them to serve as a means of earning demonic energy points.

—!

"My lord, I swear I will make the entire mountain range your domain."

"Never enter the areas I warned you about."

"Yes!"

After taking another hundred of Krutu's Poil Orcs as servants and awakening them, he set the tower in motion.

It was an exceedingly tedious affair. The mountain range was vast, and the tower was slow. The constantly changing scenery outside was quite a sight, but even that lost its appeal after a day or two.

Berge decided to inspect the tower's interior thoroughly. He would soon be leaving for the Empire, and he couldn't afford any problems.

"I don't mind either way. It's a shame I'll have to stop fighting monsters, but now I have Louise Berft."

Kaede had partially filled the gap Ernyan left, though not completely. She led the elves and taught them swordsmanship, and she had also ridden wolves alongside the orcs to hunt monsters.

It was to develop her practical combat instincts, though that had become unnecessary after Louise Berft arrived—a fighter who challenged her to spar practically every day.

"I see. So you're reasonably satisfied."

"Yes. And though this isn't something I should say as your knight, my lord, I actually think going underwater is a good idea."

"You'll fight if you must, but you'd rather avoid clashing with the Empire?"

"... Yes. I'm sorry."

"There's nothing to apologize for."

He could understand that much. No one was ever entirely free of their origins, and she had already done more than enough as his Dark Knight.

"Thank you for understanding."

"Would you like some chocolate?"

"... Oh, thank you."

The corners of Kaede's mouth rose as she chewed the little chocolate.

"Do you have any more?"

After giving Kaede a few more chocolates and sending her off, he received Elena.

"I like the sea. Besides, wherever we go, I can't leave the tower yet anyway."

"Come to think of it, you've already made your third engraving?"

"Yes."

Three engravings in only a year since she had properly begun studying magic.

Her talent truly rivaled Ernyan's. Both sisters were geniuses.

'And both of those sisters are my servants.'

He hadn't actually entered into a servant contract with Ernyan, but there was something more than that between them.

"I hear you're particularly talented at wind magic?"

"Yes. Wind magic suits me better. It's easier than other magic, and I don't feel any resistance to it. It's fun, too."

Some living beings had an affinity for a particular element. For Elena, that seemed to be wind.

"Give me your hand."

"Yes."

He took her hand and examined her interior. He could distinctly sense the mana heart formed in her heart and the three engravings within it. The mana that had once overflowed and run rampant now rested obediently inside the engravings.

'But it's not complete yet.'

Uncontrolled mana still spread throughout her body. Her mana heart was too small to contain it all. Even if she went outside, problems would arise unless she returned to the tower.

But she was close.

'The fourth engraving.'

By then, she would no longer risk her body bursting and dying from runaway mana. And it didn't look as though the fourth engraving would take very long to form.

"Would you like some chocolate, too?"

"If you're offering."

She popped it into her mouth.

"This is from the Dayleaf bakery in the royal capital, isn't it?"

"You seem familiar with the taste."

"It's the most popular chocolate in the capital. My sister likes it, too."

"I see."

"Oh, my sister likes tarts even more than chocolate."

"I didn't ask."

"You have my approval."

"What nonsense are you talking about?"

"Nothing."

"I'm just saying."

She talked exactly like Ernyan.

Elena took a few more chocolates and left.

"Sea. Sea monsters."

"You want to study sea monsters and make chimeras?"

"Yes, yes! Big one. Really big one."

Lavinia spread both arms to trace a large circle.

"A sea serpent?"

A fully grown sea serpent was a beast over thirty meters long. Its strength rivaled a high-ranking demon's, and it was unaffected by dimensional interference, making it stronger at sea than even Vivian as a Demon King.

It couldn't compare to the calamity known as Leviathan, but it was one of the strongest monsters in the sea. Capturing one would take considerable effort. In other words, it would be a nuisance.

Why bother?

"Yes."

"Denied."

"... Mean."

"Instead, I'll catch you some of the sea monsters that come near the tower."

"Yes! Volcano."

"You want to go to a volcano next? Don't be ridiculous."

Lavinia left sulking and grumbling. He offered her chocolate, but she refused, saying she didn't like it.

She looked the most childlike of them all, but her tastes certainly weren't.

"The sea? As long as I don't die, what do I care? Oh, there's one favor I'd like to ask."

"What is it?"

"Can I fight that dark elf, Gordon, too? Please? I've warned all the craftsmen to follow your orders."

She must have seen Gordon teaching Kaede.

"I'll consider it."

"I'm counting on you!"

Louise dumped all the chocolates she'd received into her mouth at once, then left with a grimace, complaining that they were too sweet.

After the princesses, he summoned Vivian.

"Why am I last? As a former Demon King, shouldn't I naturally take priority?"

"You were the last to join."

"But I'm a Demon King."

"Now you're just a high-ranking demon."

"Who do you think kept you alive? Honestly, you can't deny you'd have died without my tower, can you?"

That wasn't exactly a lie.

Merging the two towers had improved efficiency in every respect. Put another way, the tower's legs, which he had set in motion at the staggering cost of 7.2 million demonic energy points, would actually have cost twice as much otherwise.

Ever since learning that, Vivian's conceit had reached the skies. He wanted to knock her down a peg, but she wasn't wrong, so he left her alone.

"They say even pleasant words become annoying after the third or fourth repetition."

"Fine, I'll stop. But surely I can ask for one favor?"

"I haven't even told you why I summoned you."

"I don't mind going into the sea. There, satisfied?"

"What the hell are you talking about?"

"Wasn't that it? I asked the princesses..."

"You aren't a princess, Vivian Blunt. You're my servant. When I order you to do something, you do it. Your opinion is unnecessary."

"... Some of the princesses are servants, too."

"If that bothers you, make yourself more useful than Kaede or Elena."

"... This is the first time I've suffered such humiliation since becoming a Demon King."

Vivian bit her lip resentfully.

"Naturally, now that you've lost that position."

"... Then why has my illustrious lord summoned this mere demon?"

"Don't cross the line, Vivian Blunt."

"... Tch."

Having briefly reasserted discipline, Berge got to the point.

"Vivian Blunt, you're officially dead now. You know that, correct?"

"Of course."

"But neither your tower nor its Demon King was destroyed, so it wasn't summoned back to the Demon Realm. That means there's a good chance the Demon Realm doesn't know about your death."

"I suppose?"

"But they can't remain ignorant forever."

If no new Demon King arrived, the other Demon Kings would notice something was wrong. And they would soon contact the Demon Realm.

"What do you think Grand Duke Alkain will do when he learns the truth?"

"Isn't that a problem for the entire Demon Realm, not just Grand Duke Alkain?"

The tower hadn't returned. Losing one of the mere fifty towers was a painfully serious loss for the Demon Realm.

"Indeed. Then how will the Demon Realm respond?"

"Why even ask? They'll look for the reason. And if they discover you're the cause, they'll try to summon you back by force."

They would do whatever it took to establish the truth and identify the cause. If there was a problem, they would try to eliminate it.

"And if I refuse?"

"They'll cut off your support, won't they? Or order the other Demon Kings to get rid of you."

The Demon King owned the tower. Bound to the tower and the system by blood and soul, its ruler held foremost authority.

But the powers of the Demon Realm weren't so easily dealt with. The law of survival of the strong had caused countless rebellions there.

Would they really have left Demon Kings and their towers—potential rebels—without a single safeguard?

No.

The towers were connected to the Demon Realm, and the Demon Realm could sever that connection.

All support from the Demon Realm would vanish: traps to strengthen the tower, terrain alterations, summoned demonic creatures and demons. Every one of them came from the Demon Realm in exchange for demonic energy points.

Removing dimensional interference was an innate power of the tower and therefore exempt, but if everything else became impossible, that hardly mattered. With literally nothing but the tower, there was nothing its ruler could do.

"But wouldn't you be fine? You have elves, dwarves, humans, even heroes. Your only demon was the dark elf who came as your adjutant, and you have monsters instead of demonic creatures, don't you?"

He hadn't intended it, but that was how things had turned out. He could leave interior renovations to the dwarves, too, so one could argue he had no need to remain dependent on the Demon Realm.

But that was shortsighted.

"I'm talking about the future. If the Demon Realm cuts off my support, it means they've declared me an enemy. After I conquer Arain, that will cause problems whether I can return to the Demon Realm or not."

"True, but isn't that too far in the future?"

"That future will become reality soon enough. I will conquer Arain and return to the Demon Realm."

"... Of course you will, but I don't think there's anything we can do right now."

"Tsk."

Vivian was right.

'To think it would turn out like this.'

He hadn't known a tower could be absorbed, or that doing so would make the other one disappear. If he had known, he wouldn't have nodded so thoughtlessly back then.

'No, I would have.'

Without the efficiency gained by merging the two towers, he couldn't have attached the legs and moved the tower in time.

In the end, it had been inevitable.

"Very well. What was the favor you wanted to ask?"

"My servants have been left in limbo."

They had helped build the legs. But as demons, they felt an instinctive aversion to mingling with dwarves and elves. There was also no role there that the succubi could comfortably settle into.

"Isn't guarding a floor their duty as demons belonging to the tower?"

"Usually, you don't send succubi to guard floors."

"You want them to do work suited to succubi?"

"Exactly. Not me, of course."

That didn't apply to Vivian, who had surpassed the bounds of an ordinary succubus as a Demon King.

"Work suited to succubi..."

That meant seducing someone. But in the Demon Realm, the role of succubi wasn't limited to roaming dreams as dream demons.

"You want to manage the tower?"

"More precisely, we want to contribute as members of the tower. Being taken as servants and then left alone makes them afraid."

Dark elves and succubi were renowned as the two races most adept at administrative work in the Demon Realm.

But there was a problem.

"Do you know something? Even my adjutant Gordon doesn't do anything particularly significant. He spends more time idling than working."

Most of that time was spent training alone or wandering the tower. Or teaching Kaede.

The larger a tower grew, the more important managing it and its occupants became, but Berge's tower was different. Several floors were completely empty, while Kaede had the elves, Logger or Louise the dwarves, and Lavinia the monsters entirely under control. There was no need for those matters to reach Gordon.

"True, a lot of the tower is empty."

"Still, I'll mention it to Gordon. The tower will keep growing, and it wouldn't hurt for them to learn to work with him."

"Thank you."

As Vivian joyfully leaned forward, her lips met a broad palm blocking their path.

"Don't try that shit with me."

"... Didn't work."

At his growl, Vivian clicked her tongue in annoyance.

After Vivian left, Berge summoned Gordon last.

"Manage the tower properly with the succubi."

"Is there anything in particular to manage?"

"There are still appearances to maintain. How long do you think you'll have this much leisure?"

"... I'll do my best. But must you go to the Empire? It's far too dangerous."

"I can conceal my demonic energy."

"Even so... Must you enter that vault?"

Ultimately, it meant the king entering the heart of enemy territory. If his plan succeeded, he would drive a dagger into the enemy; if it failed, he would die. The tower would then be summoned back, and everything would end.

"I must."

Even so, Berge refused to yield. His eyes weren't looking at Gordon.

"Not once have I forgotten that sword."

How could he forget? It was the sword that had pierced his heart and brought him death.

"What sword?"

"No, it's nothing."

"You won't listen even if I try to stop you, will you?"

"Obviously."

"Then there is only one thing I can say. Please return safely."

"That, too, goes without saying."

Several weeks passed.

At last, the tower completed its long, long journey. Its legs began sinking into the water one by one. Fish darted away, thrashing at the thunderous noise.

At a depth of a hundred meters, the tower came to a halt beneath the now quite dark sea.

And then...

"Oh, how remarkable."

"The door is open, but the water can't enter the tower."

"I don't sense any particular magical energy."

"There aren't any engravings, either."

"How intriguing. I'd like to take it apart."

"Ahem. His Lordship has granted me that privilege."

"What?"

"If you bring me a way to strengthen the tower effectively, I can grant you that right as well."

"Oh! Really?"

"The right...!"