Crash!

As soon as we stepped inside the castle, a massive door slammed shut with a loud noise. I couldn’t tell if one of my friends had closed it to keep the demonic race from getting in, or if the demons had done it to prevent intruders from escaping.

But it wasn’t a matter of great importance. After all, we had no choice but to move forward. Even if a trap awaited us in front.

“It’s quiet…”

The Ghost Horse faded and became completely invisible as we dismounted. Anne scanned the surroundings cautiously, murmuring softly to herself.

Surely, there was a fierce battle happening outside right now, yet the only barrier was a single door, and even though the walls had crumbled with Frecia’s magic, there was utter silence from outside.

Looking around, an open lobby came into view. In a typical castle, you’d expect decorations like statues or at least some framed pictures, but there wasn’t a single adornment—it felt eerily empty, as though it wasn’t a place where people lived.

“We should go up.”

The broad lobby, which at least assumed some semblance of a castle, led into a corridor lined with many doors, but there was no need to sift through each room one by one.

After all, the ominous feeling that had lingered since we first laid eyes on the Demon King’s Castle was even stronger here.

If we climbed these stairs, we would probably encounter the source of that ominous feeling—the Demon King. And before facing the Demon King, Keltus, one of the Four Heavenly Kings, would surely block our path.

I hadn’t assumed that both Keltus and the Demon King would confront us together.

That was because, in my previous life, the Demon King never showed himself, always hiding at the top of the castle without revealing his precious face.

This time would probably be no different.

“We can’t just stand here.”

Mariel muttered as she cast a simple holy spell to illuminate the area.

Although moonlight seeped in through the holes in the walls, there wasn’t a single torch or magical light to brighten this vast space, making the mere moonlight insufficient to illuminate the entirety.

Of course, considering the battle we were about to face, it would be wise to conserve our holy power.

However, I was an assassin, and darkness felt comfortable rather than unsettling. Unfortunately, my other friends were not so accustomed to it, so we had no choice but to illuminate our surroundings.

It wouldn’t do to fight in a more disadvantageous environment just to save a bit of holy power.

Moreover, since the lighting was meant for the surroundings, it really required very little consumption of divine energy.

“Wait a moment.”

I raised a hand, stopping my friends.

As we ascended to the second floor and passed through the corridor in search of the next staircase, I heard a sound.

It was small enough to be drowned out by our footsteps echoing down the corridor, but without a doubt, a strange noise came from up ahead.

Only Mariel, focused on illuminating the hallway, seemed unaware of the sound; she was a beat late in gathering her hands to be ready with her holy power after seeing us place our hands on our sword hilts.

We waited for an ambush, but there was no sign of anyone approaching. It didn’t seem like anyone was lying in wait to set a trap.

As we stopped walking, the sound of our footsteps ceased, and through the now-quiet corridor, a suspicious noise became distinct. However, it was too vague to pinpoint exactly what it was; if I had to guess, it sounded like someone clearing their throat.

Regardless, since no one was coming despite our waiting, we had to move on. I exchanged glances with my friends, nodded, and resumed my steps.

With the Holy Sword drawn in one hand and a dagger gripped in the other, ready to be thrown at any moment.

Step, step.

As we slowly approached the direction of the suspicious sound, we stopped in front of a door.

There was no need to lean against the door to listen; the sounds from beyond were already leaking outside.

More than just the sounds coming from inside, the large double door, opened by pushing, seemed suspicious enough for anyone to notice—it was distinctly different from the other standard doors around.

Should we just burst in and go wild, or would it be better to enter cautiously just in case? After a brief moment of deliberation, I gently pushed the door.

Thanks to the well-oiled hinges, not even a creak was heard. Fortunately, after opening the door and stepping inside, we were greeted by no attacks.

“What… is this…?”

The sight awaiting us inside the room was completely unexpected.

Huge glass tubes filled the spacious area.

And within each glass tube were beings of all kinds, regardless of species—animals, humans, elves, demonic beings, and monsters—all mixed together.

“Surely they’re not going to suddenly attack us, right?”

“I don’t think so. Look closely. They’re all missing hearts.”

The common point among them was that each and every one had a gaping hole where their hearts should be.

“Ugh…”

Selian and Anne frowned in discomfort, but Mariel, looking a bit queasy, gagged.

“How pitiful to retch before the noble sacrifices. The title of Saint is really going to bring tears to my eyes.”

Squelch!

I suddenly threw the dagger I was holding in the direction of the voice that had just echoed.

Clang!

Though the dagger was infused with a sharp force, the owner of the voice effortlessly deflected it.

There was no need to ask who the voice belonged to. After all, it was a voice I already recognized.

“Keltus.”

“Seems like my introduction isn’t necessary. You are…”

The man who stepped into the light and similarly brightened the room paused for a moment, examining me. He stared directly at my face before shifting his gaze to the Holy Sword in my hand.

“Hmph, I see. You are the Hero.”

Then, he smirked, his lips curling upward, displaying a calm demeanor in front of the Hero.

“The word ‘noble’ comes from your mouth, and even a passing dog would laugh.”

“Hmm. It seems there’s been a misunderstanding. Though I had no choice but to use creatures that can’t speak, the others willingly sacrificed themselves for my research, you see?”

Keltus approached one of the nearby glass tubes, casually stroking it like it was something precious.

“Of course, they initially refused to cooperate at all. However, after my sincere ‘persuasion,’ they all changed their minds in the end.”

Clack, clack. The sound of glass being scratched sent chills down my spine.

“Indeed. This elf was the same. They were so eager to assist my research that they begged me to kill them, crying and clinging to me.”

Under the bright light, now I could see things I hadn’t noticed before.

The corpse of the elf inside the glass tube bore no signs of being intact. The pointed ears, a characteristic of elves, were roughly torn, leaving only ragged scars, and their fingernails, toenails, and teeth were all extracted. The body was covered in scars, clear evidence of having undergone all sorts of torture.

And yet, despite this, the elf’s face wore a bright smile. It was a joyful countenance that didn’t fit the numerous wounds covering their body.

Even in the moment of dying. No, rather it was precisely because they were dying that they were relieved to finally be liberated from pain.

It wasn’t just the elf in front of me.

There were countless bodies filling the glass tubes behind, beside, and all around the room, all wearing the same radiant smiles.

As someone familiar with torture, it was an incredibly surreal, brutal, and chilling sight.

If it was this horrific for me, how must my friends be feeling? I cautiously glanced at Mariel, who was already showing signs of weakness as she remained vigilant against Keltus.

She was crying.

Tears streamed down her cheeks, collecting in little droplets at her chin before falling to the floor.

These weren’t tears of fear. The emotion visible in her eyes was unmistakably sadness.

Mariel was crying for those who could not weep despite their suffering, who instead had to smile joyfully.

Grinding my teeth, I recalled memories from my past life. This situation with Keltus was clearly different from my fourth life just before this encounter.

Of course, his cruel nature remained the same, but at least such absurd experiments did not occur then.

“How grateful you are. A reckless human came seeking a transaction, and you’ve given me such an unexpected gift.”

Many things had changed since my previous lives, but it was clear where the greatest and most unfortunate change began.

“It’s truly regrettable. If only the name… was it Eden? Had been here, perhaps this experiment would have found a solution already.”

Yes. Eden.

The human who became a demon by consuming the heart of a demon.

Years after his death, the research he passed down to the demons continued to generate even more high-ranking demons and even stronger Heavenly Kings, still threatening humanity.

“In fact, the techniques that made this consumption possible have quite a few restrictions. If someone unqualified were to gain too much power, they might lose their consciousness and go on a rampage, resulting in their own demise. Conversely, some may find the power inadequate and receive no benefit at all.”

Keltus spoke with a genuinely regretful expression, babbling on incessantly.

“Still, I’ve had my research successes. What do you think? Isn’t this truly beautiful?”

Then he raised something in his hand, almost as if to show off to us.

Beauty? What a joke. Just looking at it felt ominous.

Thump. Thump.

In his hand was a pitch-black jewel. There was not a sound, nor any sign of movement, but I could definitely feel a heart beating within the gem.

“And surely, if that heart belongs to a Hero like you, it would provide a solution to my concerns.”

And then, gulp.

Keltus swallowed the jewel whole.