A massive hole had opened in the middle of the sea. Flames kept erupting from it like an exploding volcano.

"What a spectacular show."

"But that hero is extraordinary. He is no ordinary fellow."

"The Demon King will handle him."

Ernyan trusted the Demon King. She turned her gaze skyward.

"I need to do my part."

Streams of water stretching up from the sea encircled the levitation ship.

"He said he wanted it, after all."

"It is putting up quite a fight, though."

That was an understatement.

The levitation ship the dwarves had built truly was a masterpiece. Even in the spirit king's firm grip, it refused to fall. In fact, it was on the verge of breaking free.

As her mana consumption steadily increased, Ernyan realized she would get nowhere at this rate.

"I think I'll have to go there myself."

"What do you intend to do?"

"Knock all the pilots unconscious, then sink the ship intact beside the tower."

"That should be entertaining."

Ernyan took flight.

* * *

"Heavy bombardment striking the barrier!"

"Barrier damage at 31%! 33%! Rising rapidly!"

"The ship has been restrained!"

"Increase engine output and break free!"

"Engine output at 77%! Mana consumption doubles above 80%!"

Red alarms blared loudly. The levitation ship groaned from every quarter.

Its captain ground his teeth.

"Those fucking traitors...!"

Since the battle began, the levitation ship had traded cannon fire with the tower. That exchange had made one thing clear.

Dwarves had undoubtedly built those mana cannons. Only the finest equipment in the Kingdom of Berft was installed aboard the levitation ship. There was only one group capable of making mana cannons equal to its own:

The royal workshop's craftsmen, who had built the ship's cannons.

'This couldn't be worse...!'

The power of the Heavenly King called the Dark Spirit Summoner had bound the levitation ship. They were struggling desperately to escape, but it was proving difficult. Meanwhile, the tower's mana cannons kept pounding the vessel.

The barrier was wearing away by the second.

By contrast, the tower appeared unscathed by their bombardment. He had no idea what it was made of, but he thought he understood why humans never tried to destroy towers from the outside.

'Damn it. I'd love to take it apart and see what it's made of.'

Suppressing his racial instincts, he issued his orders.

"Feed in every mana stone we have! Turn the guns away from the tower and toward those chains of water. Once a full volley weakens the chains, raise output to maximum and break free!"

"Yes, sir!"

"We only get one chance, so stay sharp!"

It was then that a tremendous impact shook the hull.

"C-Captain!"

"What is it?"

"An enormous water giant is approaching. The water it fired struck the barrier!"

"What?"

"A Heavenly King! We can see the Dark Spirit Summoner! She's approaching!"

"The Dark Spirit Summoner...!"

The captain ground his teeth. The ship was restrained, reduced to an immobile punching bag. They had to maintain maximum output and worry about both rapidly dwindling fuel and an overloaded engine. Ultimately, it was all her fault.

"Fine. You want a fight?"

Just how little did she think of dwarves and their levitation ship, to dare do this?

"Turn every gun! Target the Dark Spirit Summoner! Blow her away with a full volley!"

"But what about escaping...?"

"That bitch is the one who put us in this mess! Don't you know spirits are forcibly sent back when their summoner dies?"

"Y-Yes, sir!"

The guns changed targets, aiming at the enormous water giant and the Dark Spirit Summoner charging toward the ship.

The dwarves' masterpieces spat fire. Some shots merged while others split, tracing long arcs.

BOOOOM!

They struck the water giant. Explosions erupted, piercing and crushing it until it ceased to exist.

"We got it!"

"What about the Dark Spirit Summoner?"

"She's unharmed!"

Using the giant as a sacrifice, the Dark Spirit Summoner had drawn even closer.

"Distance approximately thirty meters!"

She was too close for the mana cannons. Their destructive force would damage the ship itself.

But mana cannons were not the levitation ship's only weapons.

"Discharge the Lightning Whip!"

"Discharging!"

Mana flowed into an artifact engraved with lightning magic.

CRACKLE!

A lightning whip split into hundreds of lashes and struck at the Dark Spirit Summoner.

But a shield of water sprang up and blocked them.

"It failed!"

"Ten meters!"

"Water should conduct electricity! What the hell is wrong with it?"

"Captain! This isn't the time to complain about—"

"I know! Activate the repulsion spell!"

"Activating repulsion spell!"

The engine spun furiously, pouring out heat as the magical engravings covering the levitation ship activated.

BOOOM!

A repulsive force pushed everything away. In an instant, the Dark Spirit Summoner was thrown dozens of meters backward.

"Fire the mana cannons!"

"Full volley!"

Once again, the mana cannons blazed with light.

This time, there was neither a water giant nor a shield. A massive explosion engulfed the area.

GULP!

The dwarves swallowed hard.

"Did we get her?"

At that very moment:

"Captain! An enormous mana fluctuation fifty meters above the ship...!"

"What? Put it on the screen now!"

The recording orbs installed throughout the vessel transmitted images of the outside.

"My gods."

The captain cried out.

It was a spear of water—an immense mass of compressed power containing terrifying mana.

Dangerous.

Every dwarf recoiled in horror.

"We can't escape, can we? Damn it."

The chains of water still held the ship fast. He shuddered at the thought that one person could truly be doing all this.

'Are they the Four Demon Kings rather than the Four Heavenly Kings?'

"It's descending!"

"Deploy the shield spell!"

Separate from the automatic defensive array, a translucent shield appeared like an umbrella over the levitation ship.

"Impact imminent!"

BOOM!

The shield shattered instantly. Should they be impressed that it had at least slowed the spear a little and weakened its power?

"Release flames!"

"Release flames!"

Flame cannons, distinct from the mana cannons, spewed fire in unison.

The aim was to evaporate at least some of the water forming the spear and weaken it.

It worked. Steam billowed and the spear weakened. But it continued falling all the same.

BOOOM!

The levitation ship shook.

"Impact!"

"Barrier damage at 45%! 51%! Rising rapidly!"

CRAAACK!

It seemed they could hear the barrier cracking. The captain went pale.

"Concentrate power overhead and reinforce it!"

"That will weaken the sides!"

"The top is about to break! Do you think we can worry about that shit now?"

"Yes, sir!"

The overhead barrier thickened further. Slowed by the shield and weakened by the flames, the water spear lacked the strength to penetrate it.

"Spear dissipated!"

"Damage at 66%! Bombardment against the weakened sides is intensifying!"

"Start repairs immediately and find the Dark Spirit Summoner! This won't end until we kill that bitch!"

The captain ground his teeth at that monstrous power. Even hundreds of mana cannons would not have caused this much damage. The barrier was the levitation ship's crowning achievement, the part they had put the greatest care into designing.

'What the hell is that bitch?'

How could a mere subordinate of a Demon King possess such power?

"It's all right. There's no need to look."

"What nonsense is that?"

"I'm already right here beside you."

"How could the Dark Spirit Summoner be beside me... Huh?"

"Huh?"

"C-Captain?"

The captain turned his head stiffly, like a malfunctioning golem.

A smiling, masked woman stood there.

The very woman who had been charging toward the ship from outside mere moments ago.

"H-How?"

"Your barrier was very sturdy, so I broke through at a single point."

Destroying the entire barrier at once was beyond her, but she could create a tiny crack with the spear. She had thrown herself through that gap.

It was possible because the levitation ship's barrier system was not a single, complete structure, but one that constantly regenerated.

"... K-kill...!"

The captain went limp and collapsed.

"C-Captain!"

"You monster!"

Several dwarves charged with weapons drawn, but droplets of water blocked them and brought them down.

"Now, you have two options."

The Dark Spirit Summoner held up her fingers.

"One: do as I say and quietly go under the sea."

She folded one finger down.

"Or resist, get knocked unconscious, and be dragged there by force."

One dwarf raised a hand.

"What is it?"

"I-Is there another option?"

"There is."

"Reall—gah!"

"Ask strange questions, get knocked unconscious, and be dragged there by force."

"..."

"..."

The dwarves turned deathly pale.

"W-We'll go quietly."

"So will I."

And so the dwarves' ultimate weapon plunged into the sea of its own accord.

* * *

"Remarkable."

Reina Sordein was central to this battle. That was inevitable once they decided to meet the heroes outside the tower—and at sea, no less.

The demonic creatures were no more accustomed to the sea than the heroes. She had to keep freezing it to provide a proper battlefield.

She was also the only commander who could smoothly coordinate both the demons and the demonic creatures.

Thus, she issued orders from one side of the battlefield, observing everything.

She had witnessed the exploits of those called the Four Heavenly Kings.

"All the Stars have fallen."

Stars. Reina knew full well how much that title meant to humans.

Two or three of them together were quite capable of killing a Demon King. Countless Demon Kings had died that way, most recently Drakson and Ugar.

They were by no means weak. The Four Heavenly Kings were simply stronger.

She could not decide whether the princesses were extraordinary, or whether Berge was extraordinary for bringing them together and making them his servants.

One thing was certain: they had gained the upper hand.

'What if I had been alone?'

She would have lost. There was no room for doubt; defeat would have been certain.

Balaf Dislord, Roselle Charnt, Watton Collo, Pablo Barkat, Aina Diaphrin, and Ralph Schmitz.

Six whole Stars. And the terrifying fluctuations of mana and demonic energy from the battle deep beneath the sea told her that Balaf Dislord was stronger than she was.

The Stars would have swept away her high-ranking demons.

Then that monster Balaf Dislord, who scarcely resembled a hero, would have cut off her head.

After more than a century in Arain, she had nearly become a foolish Demon King who, far from conquering the dimension, endured mockery and wasted her time only to lead every servant who had trusted and followed her to their deaths.

Just then:

RUMBLE!

A roar shook the battlefield, drawing Reina's gaze upward.

A lone human was locked in fierce battle with the dwarf kingdom's final bastion.

'Ernyan Hilderan.'

The Crown Princess of the Kingdom of Hilderan, and Berge's servant. All the Four Heavenly Kings were exceptional, but the others fell short compared to her.

'A spirit king's contractor...'

Spirit kings were rulers who reigned over the higher dimension known as the Spirit Realm.

Unlike Demon Kings, who were kings in name only, they were true kings. Though each of the four great spirit kings would fall short of the Demon Emperor, master of all demons, in individual might, they could not be dismissed.

Her reflections did not last long.

RUMBLE!

The fluctuations in the sky vanished. The chains of water fell away, and the levitation ship hurtled toward the sea.

Reina realized Ernyan had won.

"Th-The levitation ship?"

"Why is it going into the sea?"

"They should be supporting us with cannon fire!"

The heroes screamed as the demonic creatures' offensive intensified in the absence of the bombardment.

At the same time:

BOOM!

Scorching heat originating deep beneath the sea pierced the sky. With it, all the demonic energy vanished.

The battle had been decided.

'If the victor... isn't Berge.'

Reina calmly gathered her demonic energy.

Berge was still alive. As his servant, she could tell. But what if that monster Balaf Dislord had captured him and was keeping him barely alive?

'I'll ambush him when he comes up with his guard down and rescue Berge.'

That was the best she could do.

Fortunately, there was no need.

"Berge!"

It was Berge who emerged. Balaf Dislord's limp body was so ravaged that she could almost mistake him for a corpse.

"G-Guildmaster!"

"Balaf—no, the Guildmaster has lost!"

"My gods! First the Stars, and now the Guildmaster!"

The Guildmaster's defeat, following the Stars' defeat and the levitation ship's fall, was the final nail.

The heroes' morale plunged past rock bottom and into the depths of the sea.

"W-We have to run!"

"Where? Our ship has gone down!"

They panicked. At that moment:

"Hello, everyone. This is the Dark Spirit Summoner."

The falling levitation ship stopped just before entering the sea.

A lovely voice flowed from its sound amplification system.

"The battle is decided."

"Your levitation ship has been seized, so you've lost your means of escape."

"The levitation ship was captured, not shot down?"

"Those stupid dwarf bastards! They call it their treasure, but they can't even protect it! What the hell are they doing?"

"I have a proposal."

"Surrender."

"Otherwise..."

ROOOAR!

A thunderous noise erupted.

"Th-That...!"

"A wave!"

"It's a tidal wave!"

The heroes saw it: a ten-meter-high tidal wave rushing toward them.

"Aaaaah!"

"Save me!"

The heroes panicked, but there was nowhere to run.

The Dark Spirit Summoner's calm voice slipped through their cries.

"You'll all die."

Fortunately, the tidal wave stopped right before them. But the heroes could not feel safe.

"Now. Surrender."

Instead, they were horrified and plunged into despair at the Dark Spirit Summoner's ability to create a tidal wave and bring it to a halt.

"I will spare your lives, at least."

Every hero lost the will to fight.