Chapter 508 – In the Depths of the Undersea City

The areas destroyed by the lava were still emitting intense heat, making it difficult to approach immediately. During that time, we proceeded with our next actions.

In other words—by dividing them with a barrier, we would prevent them from escaping. Then, we would carry out purification and a direct assault.

As for me, I temporarily returned to the deck, drank a Magic Potion, and prepared for the next move. Meanwhile, Old Sigmund, Valentina, Charlotte, Forset, Princess Stephania, Princess Adriana, and Auria took their positions.

The barrier expanded around the fissure and the castle, sealing off the battlefield from the outside world.

If… the enemy were to flee, they would have to retreat back into the depths of the fissure. Although the end of the fissure was a dead end, it was important to leave them an escape route. If they had no way out, they would put up more resistance than necessary, which would only increase our casualties.

The reason we were calling out to them, promising to spare their lives if they surrendered, was to avoid creating such a situation. Therefore, the enemy had three choices: stay and fight, open the castle gates and retreat into the dead-end fissure, or surrender.

“Shall we begin, then?” Claudia said, and Marlene nodded softly.

As Marlene made a gesture of prayer, the bodies of the assault team, including mine, were enveloped in the Moon Goddess’s Blessing. It was a necessary measure for charging into a castle swirling with Evil Energy.

Combined with Tephra’s Blessing and Marl’s Blessing, it would likely prove effective enough in our battle against Waldom and his subordinates.

“Then, we shall be off.”

“Indeed. We shall do our utmost to ensure our magic aids you in your fight.”

“May fortune favor your arms.”

The glow of the Magic Circle deployed by Queen Eldorene, Rovisa, and the Water Guardians intensified.

The Evil Energy clinging to the castle wavered as if stirred by a fierce wind.

“We’ll sing our hardest too.”

“So… please come back without getting hurt.”

“Theodore-sama, please be careful.”

Justia, Dominique, and Cyrille. And the Sirens, led by Marion, also came to see us off before our sortie.

“Yeah. I’ll be back.”

After replying to them, I turned my gaze to Grace and the others.

“We’re ready as well.”

“We shall accompany you, Theodore-sama.”

“That’s right. Let’s go finish this.”

I nodded at the words of Grace, Ashley, and Rosemary.

Creating bubbles of water, we took measures against the high temperatures near the entry point.

“Alright, let’s go.”

Sheila took off from the deck, and I followed.

The assault team consisted of the Party Members, Sion, Marceska, and Sigritta. The remaining members stayed behind as reserve forces to handle any external movements. The queens stationed on the Sirius would maintain and defend the barrier, and depending on the situation, they would assist the soldiers with support or help storm the castle.

Corulis, clad in crystal armor, waved goodbye alongside Princess Stephania. Corulis was part of the barrier team’s escort group. I, too, smiled and waved back at the barrier team before plunging into the castle.

Through the shattered gap, we leaped into the castle’s interior, swirling with Evil Energy—into the audience chamber. There, a massive Magic Array was drawn on the floor. Judging from its design, it seemed to be for amplifying Evil Energy.

The Evil Energy drifting within the castle was still thick… but the amplification had stopped the moment the Volcanic Hammer struck. The Magic Array had been shattered along with the floor, partially swallowed by lava, and appeared to be non-functional.

There was no sign of the enemy. —However, from the passage leading deeper into the castle from the audience chamber, a powerful Evil Energy was flowing.

“It seems it’s down that passageway.”

We all advanced deeper along the passage. In the magnificent corridor, several Subordinates were floating with their eyes rolled back.

They seemed to have fainted. Grabbing one by the leg, I lightly checked its condition with Circulating Ki. …It appeared to have sustained significant damage to its hearing. Well, the explosion was tremendous even from the outside, so it must have been even worse inside the castle. At any rate, these ones were in no state to fight. This should give our soldiers an advantage when dealing with any remaining stragglers inside.

That much was fine. Those who fainted from the aftermath of the Great Magic were never a concern to begin with. The problem was… those who managed to respond to that earlier strike.

They likely possessed considerable strength. And… Waldom, the source of the Evil Energy. Unless we defeated him, the battle wouldn’t end.

We knew his location. If we kept heading in the direction of the powerful Magical Power, we would naturally reach him. Proceeding cautiously through the corridor, wary of ambushes, we emerged into a fairly large hall.

It was larger than the audience chamber. From the structure of the building, it resembled a temple… That’s right. This must be the Mausoleum of the Benevolent Mother that Queen Eldorene had told us about. There was even an altar.

At the far end of the mausoleum, beyond the altar, there should have been a statue of the Benevolent Mother… but it was tragically shattered from the torso up. And as if using the shattered statue as a pedestal, a massive crystal shimmering with a purple light was enshrined.

And guarding that crystal, from atop the altar, the Subordinates and a single Monster glared down at us.

The source of the Evil Energy filling the castle. And seeping faintly from the cracked crystal was… something far more sinister than mere Evil Energy.

It was—Miasma. And within the crystal, from which Miasma leaked, a humanoid silhouette squirmed. Inside was Waldom… and the crystal trapping him was the Seal placed by the Benevolent Mother.

“A Demon…” Rosemary murmured. Not just the Demon inside the crystal—there was another one that caught my attention.

“Theo, that monster…” Grace frowned.

The Monster moving alongside the Subordinates. Its front half resembled a killer whale, but its back half consisted of countless tentacles, like those of an octopus or squid. And beside it—stood a single man. He and the killer whale monster were touching the crystal, using some sort of Spell Formula to channel Magical Power into it.

Ah. I understood what Grace meant. The dorsal fin of that monster looked familiar.

Yes… It reminded me of the time we fought the Blazing Heat Zevion. It resembled the monster that served as the messenger for the Demons we let escape.

However, it wasn’t surprising. We had anticipated this as one possibility and discussed it—the scenario where Waldom’s faction was connected to the Demons. In other words, there was a possibility that Demons were behind the Subordinates.

First, it was safe to say that Waldom himself was a Demon specialized in the ocean. That seemed correct given the circumstances. And then, the other one… that man using a Technique on the crystal Seal…

“Truly… unexpected. I never imagined a land-based Magician could exert such power here at the bottom of the sea,” the man channeling Magical Power into the crystal said. His appearance resembled a human’s… but he was cloaked in Miasma.

And there was a Magical connection visible between him and that killer whale monster. That meant they were in a master-Familiar relationship. This guy. He must be the original messenger.

Waldom, the Demon… likely promised cooperation to Valros and the others in exchange for having his Seal released… or something along those lines.

And then, after subjugating the ocean, they would coordinate an attack from the sea when the decisive battle in Termwills commenced.

“You… are a Demon?”

“Yes. That’s correct.”

Saying that, the man closed his eyes.

If he had a connection with Linette, it would be possible for him to acquire such a Familiar, and it was highly likely he had been taught a Spell Formula to weaken the Seal. For Linette’s experiments, the Sea King’s Seal would have made a perfect sample before the real thing.

At any rate, this man was an ally of Valros and the others. After their method of communication in the ocean was exposed during the Zevion incident, they probably grew cautious and sought alternative means.

Their aim was likely… to weaken the Seals on the Subordinates imprisoned in the ocean and release them.

From what I could see, that Familiar was also involved in breaking the Seal. That’s why they couldn’t dispatch it as a scout until the Sea King’s Seal was undone. Prioritizing the release of the Sea King’s Seal over searching for mermaids was understandable, I suppose.

“…My name is Oberk. If my assumptions are correct, you all… no, you are the Demon Slayer, aren’t you?”

Oberk slightly opened his eyes and looked at me. The Familiar… was pursued by the Knight Order back then. We ultimately let it escape, but it seems the information about the Demon Slayer hadn’t reached the Demons’ side.

“Judging from the timing… were you the one who weakened the Seal?”

Oberk didn’t answer. He only smiled faintly.

“Indeed. We are those who have served His Majesty Waldom since ancient times. With Lord Oberk’s assistance, we have risen from the deep abyss.”

One of Waldom’s Subordinates—his aides—spoke. It resembled a dragon, but… the shell on its back was likely its own. It seemed to have originally been a turtle monster.

“I never imagined the Demon Slayer would be such a child… but after witnessing that Great Magic,” the Subordinate next to it said. To describe it, it was as if a whale had taken human form, with a single long horn sprouting from its forehead. This one held a massive Spear befitting its huge frame.

Both the dragon-turtle and the whale… the Sea King’s Subordinates were emanating Evil Energy, not Miasma.

They were different from Half-Demons. They were likely the fallen remnants of Monsters that served the Demon.

At any rate, we understood the background. Now, all that remained was to Smash them to pieces.

As I took my Stance with Ouroboros and raised my Magical Power, Oberk’s expression twisted.

“The Demon Slayer… I see. You do possess power on a different level. We certainly cannot fight you, but—what about your comrades? We shall at least serve as His Majesty Waldom’s vanguard.”

Saying that, Oberk materialized a Greatsword.

“Indeed. And—we shall settle a long-standing grudge. Though the weak Subordinates were a disappointment… no matter. If we strangle the Mermaid Queen directly and tear out her Magic Stone, it will soothe my resentment. In fact, it’s rather convenient. If you interfere—Demon Slayer. I will kill you too.”

A cold voice echoed through the mausoleum. The crack in the crystal grew larger. A fist burst out from within, as if shattering an eggshell, and an enormous amount of Miasma spilled forth.

The Sea King Waldom. From beyond the shattered crystal, the Demon slowly revealed himself. A man with blue hair and an intelligent appearance.

A form resembling a human, ill-suited for the deep sea—or so I thought, when fins sprouted from his arms—and his body transformed into one suited for underwater activity. Oberk did the same.

…Right. That made sense. Though he called himself the Sea King, if his true identity was a Demon, his original form should have been human-like. The title “Sea King” was merely self-proclaimed.

“Thinking about it… this is unfinished business from our fight with Zevion. This time, we won’t let you escape.”

Saying that—Grace, enveloped in Fighting Spirit, took her Stance with her Dual Axes.

Yes. That’s right. Whether Waldom is a Demon or Valros and the others are pulling the strings, what we have to do doesn’t change. We’ll crush them thoroughly and move forward.