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“Kyah!”

As I looked around, I couldn’t help but think that the room was quite spacious, perhaps using nearly the entire floor. The room was densely filled with test tubes containing the corpses sacrificed by Keltus’s experiments.

Naturally, counting them one by one was meaningless; it seemed to be in the dozens, if not hundreds. There were various types of corpses as well, ranging from ferocious beasts like bears to ordinary humans, hideous monstrosities, different races like elves and dwarves, and even those of the demonic race like Keltus himself.

SMACK!

There were so many of them that as they trampled over each other, I swung my sword at one that had approached within arm’s reach. However, it sounded more like a dull thud rather than the sharp sound of flesh being cut, indicating that Keltus had likely done something else to the corpse.

The good news was that they resembled ghouls or zombies, so while their bodies were tough, individually they posed no significant threat. After forcing through the resistance I felt at the tip of my sword, I kicked the body away.

But that was just one of them; hundreds remained.

Though the horde of corpses before me felt threatening, what worried me even more was the whereabouts of Keltus.

Since those corpses obviously wouldn’t recognize him as an ally, it would be quite troublesome for us if he decided to use them as shields while casting magic from a distance.

But instead of attacking us, he simply turned his back and vanished somewhere. That satisfied smile he wore only added to the ominous atmosphere.

Not that he was cunning by nature, but there had to be some scheme behind his sudden disappearance. I knew I should chase after him immediately, but the swarming corpses kept me rooted to the spot.

“Grar…”

How long had we been huddled around Mariel, who was preparing another holy magic to break through our current predicament? Suddenly, I heard a sound from behind that resembled a beast’s roar.

It felt oddly familiar rather than truly threatening. I swung my sword at the nearby enemies and glanced back towards the source of the sound.

A girl with beautiful red hair reminiscent of roses was moving gracefully. However, with every movement, I could catch glimpses of her intense gaze, and amidst all the noise, her voice held no trace of her floral beauty.

“Kyah!”

As the corpses screamed, Anne countered with an even louder beastly roar. I had seen this before once.

At that time, she had lost control, overwhelmed by the blood surging through her, reacting to Vulcan’s magic as one of the Four Heavenly Kings. I had thought she would be calmer around Keltus’s magic, but it seemed she was instead responding to the rampant aura surrounding the corpses.

Without hesitation, Anne leaped into the thick of the corpses. Even wielding her great sword with one hand, she effortlessly tore her way through the bodies that split apart in all directions.

With her other hand, she grabbed whatever she could find to throw or used her fists, causing the heads of the corpses to explode with her overwhelming strength.

While we had almost been overwhelmed during the struggle of covering each other’s backs, Anne’s wild display drew the attention of the corpses, making it slightly easier for us to defend than a moment ago.

As Anne single-handedly crushed dozens of them, Selian and I stayed close to Mariel, cutting down the incoming foes.

Now as the unmoving corpses formed small mounds around us, Mariel finally completed her long preparation and spoke.

“The Lord descends upon this land; may His light shine.”

With her declaration, a bright light radiated from her. As the light expanded, the moving corpses had no choice but to come into contact with it, each one igniting in flames upon touching the light.

The holy magic Mariel had just used was a sacred magic exclusive to saints called Sanctuary Declaration.

It required a tremendous amount of mental and divine energy, so normally she would have saved it for facing the Demon King. However, given the urgent circumstances, it was a choice with no other alternative. After all, even though Anne was doing great, she couldn’t keep going without tending to her own wounds forever.

True to the name of Sanctuary Declaration, at this moment, this space lit up by Mariel could be deemed more sacred than anywhere else on the continent.

Thus, no matter the number, mere corpses had no means of penetrating the light.

However, being within the domain of the demonic race, particularly deep within the Demon King’s Castle presented a minor issue of it being temporary and limited in range.

Perhaps with no self-awareness, the corpses instinctively realized the harm of this light and seemed to shrink back, providing us an opportunity to bounce out and break through.

“Graaaah!”

As I ducked behind Anne, she instantly sensed my presence with her beast-like instincts and let out a fierce cry. The memory of almost being crushed by her rose to the forefront, but I quickly grabbed the collar of her nape.

“Sorry! I’ll ask for forgiveness later!”

With the significant difference in our heights, I swiftly threw her toward the safety of the light before she could bounce around back toward me. Then, I followed her straight into the light.

“Ugh, my head…”

Perhaps due to the sanctified light calming the surge of blood within Anne, the wild beast that had just rampaged was now rubbing her head and regaining her senses.

The reason Anne had a headache was… well, it was because she had regained her sanity, not because she hit her head on the floor when thrown. Maybe.

“There are just too many…”

“At least fortunate for us, each individual isn’t that powerful.”

Taking a moment under the protection of the sanctuary, we exchanged words. It hadn’t struck me during the frenzy of swinging swords, but from afar, the sheer number of corpses looked grotesque.

“But now that we’ve cast the Sanctuary, if we take our time to take them down one by one…”

Before I could finish my sentence, Mariel suddenly shut her mouth, her face stiffening, as did Selian and Anne, all gripping their swords tighter.

“I felt it from above.”

The sense of impending doom that had lingered since we first caught sight of the Demon King’s Castle felt stronger now that we were inside as it seemed to engulf my whole body with an explosive force.

Even while incessantly swinging my sword, I felt a cold sweat break out as my body reacted to the sudden aura, which had come out of nowhere.

“Could it be…!”

The looming dread was even greater than when I faced the jet-black jewel brimming with curses. There couldn’t possibly be more than two entities on the continent exuding such an ominous aura.

“The Demon King…”

As Selian uttered that ominous name, I instinctively tensed and swallowed hard.

“Was this the reason Keltus restrained our movement? We can’t afford to stay here any longer.”

The evil presence above hadn’t fully revived the Demon King yet, but the sensation of foreboding was continuously increasing. Thinking it was fortunate that it hadn’t fully returned yet, the looming energy felt far from benign.

“Phew… as always, it’s happening again.”

Selian sighed deeply and turned to me. Glancing at her, I noticed that both Anne and Mariel were looking at me, their brows slightly furrowed but, thankfully, their expressions relaxed.

Even without me saying anything, it seemed my friends could anticipate my next words.

Indeed, I had committed grave acts that warranted their resentment.

Besides, I was the only one fast enough in this group to burst through the horde of corpses, and I was also the only one capable of standing against the Demon King.

“Even if you try to stop me… that won’t help, will it?”

“In this situation, it’s the best option. But now that I can call myself a hero, you shouldn’t worry too much.”

“How could we not worry? We just… trust you.”

Mariel approached, resting her hand on my head and speaking in her gentle tone. Then she lightly tugged my hair and planted a soft kiss on my forehead.

As the blessing of the saint enveloped me, my body, which had worn down a little from battle, was revitalized, overflowing with energy, and even felt somehow better than when I was in prime condition.

“If you go out there and get hurt, I’ll be sure to hit you later, so keep that in mind!”

Hey Anne? You’re not referring to me as the one you’ll hit, right?

“Then I’ll go ahead and defeat the Demon King, so take your time to catch up.”

I dashed toward the stairs leading upwards, trying to ease their worries as I went.

*

“I thought perhaps, with this power, I might take you down. You truly are the hero.”

While fighting, I had completely absorbed the jet-black jewel. Yet even after exerting my full strength, the hero faced me instead of collapsing.

Reluctantly adhering to my original plan, Keltus hastily worked to entangle the hero party’s feet with the horde of corpses. Despite the corpses being one of his trump cards, it wouldn’t be reasonable to expect the hero to fall for it. They might only afford him some time.

Meanwhile, he had to finish the task he was originally meant to do.

With each flight of stairs climbed, Keltus made his way to the highest point of the colossal Demon King’s Castle.

Standing before a door grander and more ornate than any other, Keltus adjusted his attire momentarily before lightly knocking.

After a brief wait with no response, he cautiously opened the door and stepped inside.

As he walked along the lengthy carpet, he arrived at a higher section within the room, leading to the very peak of the Demon King’s Castle.

“The Demon King.”

Naturally, the occupant could only be the Demon King.

Keltus kneeled before the Demon King, trying to pay his respects, but received no reply. The Demon King simply sat expressionless, gazing down from the throne.

Perhaps it was because he hadn’t fully revived yet.

Though only a half-formed Demon King, Keltus had no intention of allowing any disrespect in his presence.

However, the endless waiting had come to an end.

Until now, he’d been forced to wait idly for the Demon King to regain his strength, but thanks to a technique he had randomly acquired from someone who had turned his back on humanity, he found a way.

Of course, as he had told the hero earlier, this technique of gaining power by devouring hearts came with several drawbacks.

If bestowed upon an unsuitable individual, one would lose their self, while if given to a being of higher caliber without proper compatibility, it wouldn’t aid them at all.

In fact, no matter how many high-ranking demon hearts he offered, they didn’t assist the Demon King in regaining his strength. It simply wasn’t fitting for his rank.

Indeed, not with mere high-ranking demons.

THUMP!

Still bowing to the Demon King, Keltus drove his blackened hand into his own chest.

Though he gouged his heart with razor-sharp claws, his form gave off a grotesque sight as not a single drop of blood flowed. It was as if he were too stingy even for a single drop.

Regardless of the toughness of the demon race, one could not survive without a heart. Yet Keltus, being a member of the Four Heavenly Kings and a strong demon next to the Demon King, could feign death for a brief while.

In that fleeting moment, Keltus grasped the heart he had just removed and lifted it slowly.

“I offer this to you.”

The jet-black jewel crafted from the deceptions of countless life forms. Undoubtedly it held great power, but it was still insufficient for the grandeur of the Demon King.

However, what if it were Keltus’s own heart? It might just bridge that gap — a process of honing meant solely for the battle with the hero.

The Demon King, who had only been watching, finally stood and approached Keltus at a slow pace. He reached out and took the heart Keltus held, bringing it to his lips.

Keltus, still kneeling, could only look up.

As the Demon King took a bite of his heart, small pieces of it began to disappear, but Keltus displayed no signs of pain; rather, his expression beamed with joy and ecstasy.

“Ah… our eternal master. Under your existence, all shall kneel…”

And when the last remaining piece finally vanished into the Demon King’s mouth, Keltus accepted his death, feeling that his wish had finally come true.

*

With the exception of the demons outside, it was obvious that all others fell victim to Keltus’s experiments, leaving no diabolical guards standing to impede my path. The structure above was relatively simple compared to the lower floor, which had the hall and laboratory.

Eventually, I reached a colossal door that looked suspicious to anyone. It bore a resemblance to the audience chamber of the Emperor, yet the ominous atmosphere felt entirely different.

The sense of danger still lingering in the air undeniably pointed to the fact that the Demon King awaited on the other side.

Additionally, Keltus, who had battled us before, might also be waiting with the Demon King.

It was a perilous situation, but I couldn’t afford to hesitate any longer. Without a moment’s doubt, I kicked the door open and rushed inside.

The long corridor stretched ahead, where I spotted a figure at its end.

Though it was dim, there was no mistaking it; it was the Demon King.

Slowly, I approached, a mix of tension and vigilance running through me as I searched the surroundings for any other impending threats, but thankfully Keltus seemed to be absent.

By the time I drew near enough to make out each other’s faces in the darkness, the clouds that had hidden the moon parted around me thanks to Frecia’s magic, illuminating the room.

The Demon King turned slowly to face me, his only rival, the hero, displaying no change in expression. He simply adorned his armor from thin air and drew his sword.

Watching this unfold, I could only stand there, dumbfounded, rather than swing my sword.

There,
was the Demon King ‘me’ staring back at the hero, ‘myself.’