Returning to the Mysterious Era

"Let's go with Cell No. 3."

Ole didn't hesitate at Cassius's choice. He immediately grabbed a pen from his pocket and circled a spot on the notebook he was carrying.

The group then headed toward the distant bunker. To the right of the semicircular fort protruding from the ground, a spiral passage leading downward appeared. There were Black Ops Agency officers dressed in black, stationed at the entrance, each with a bulging gun holstered at their waist.

As they descended along the passage, the group of four soon arrived in a spacious hall. The area below this cell was even larger than Cassius had imagined, at least half the size of a football field. Roads extended on both sides, leading to unknown destinations.

Halfway through, a young man took Ole's place to lead the way, while Ole himself made his way toward the research lab.

He quickly pushed open the door, where an old, bald man with bat-like hair was tinkering away with a test tube filled with a thick, mud-like substance. The old man wore a coat similar in style to a white lab coat except black. A pair of glasses, thick as the bottom of a beer bottle, perched on his nose.

"Dr. Tommy, they're here," Ole said as he closed the door behind him.

"They've arrived?" The old man quickly set down the test tube and tidied up his messy desk. Together with Ole, he hurried toward Cell No. 3.

"Dr. Tommy, do you really think someone can handle these undead evil spirits? We've tried various methods over the past few years to deal with that dark creature in Cell No. 3, codenamed 'Slender Black Shadow,' but the most we could do was badly weaken it. Explosives, fire, bullets, and electric shocks all had no effect," Ole said as they walked.

"The way I see it, there has to be some kind of way to deal with any dark creature. They all have weaknesses. We simply haven't found the right method yet, so we can only confine them in cells," Dr. Tommy said, pausing for a moment before continuing, "I've researched them over the past decade or so, so I know there must be a way. However, finding the correct weakness for a specific dark creature is incredibly unlikely. Even if we do find it, it would only apply to that particular type of dark creature. It wouldn't have a universal effect on any other specific dark creatures. That's why we have all these issues piling up in the cells."

"So, you don't have much confidence in them," Ole said after a moment of silence.

Dr. Tommy nodded.

"Of course not, but who knows? After all, this person was recommended by the previous and current chief administrators of the agency's headquarters. Maybe they have a special method." Dr. Tommy shook his head faintly. Then, noticing Ole's silence, he continued, "You're thinking about your daughter, aren't you? Being parasitized by a dark creature, her willpower has been twisted to madness. And because of the dark creature's particularity, even death isn't a possibility. You can't save her… Let's hope this man named Li Wei has a way. A quick death is better than living through endless suffering."

Two minutes later, they arrived at Cell No. 3.

The group stood in front of the door, peering into the cell through a special glass. It was a room five meters wide and ten meters long. Inside, there was nothing but emptiness, except for a white humanoid statue standing in the center. Behind the statue, a long, slender black shadow, resembling mist, lay motionless, like a crocodile basking in the sun on the riverbank.

"There are countless types of dark creatures. Aside from some populous groups, there are also many rare and unique types. Because these dark creatures are so few in number, it's hard to determine their weaknesses, so they're usually confined in cells," Ole explained, flipping through his notebook.

"Cell No. 3, codename 'Slender Black Shadow,' was captured five years ago. Before its capture, it had already killed at least fifty-two people, and five Black Ops Agency officers lost their lives trying to catch it. It's a very dangerous type.

"It's similar to a shadow, yet it also mimics mist. It attaches itself to living people from behind and stays connected until they have completely drained the victim's body. Afterward, it detaches itself, in search for the next prey.

"If you enter Cell No. 3, you'll be attacked by the Slender Black Shadow immediately, similar to the ferocious pouncing and tearing of a feline. It will display strength and speed far beyond that of humans. One thing to note is that you must not turn your back to the shadow. If it attaches itself to you, it will enter a semi-intangible state that's difficult to engage with. Its hands will grip on tightly, squeezing the life out of the victim until they are suffocated to death." After finishing his explanation, Ole stepped aside.

Amos and Franz exchanged glances with Cassius, and the three nodded. Franz handed the key he was holding to Cassius.

"I'll stay at the door to prevent any unexpected situations," Amos said, adjusting his round glasses, the lenses reflecting a faint light.

"Alright," Cassius replied.

With a click, he promptly opened the door, and stepped into the cell, walking steadily toward the center. Meanwhile, Amos stayed by the door, white gloves spreading a web of metal threads that climbed onto the door frame, forming a spider web-like barrier.

Cassius walked toward the white statue.

The Slender Black Shadow seemed to sense the presence of a living person. It started trembling with excitement, its mist-like body thickening. It turned sharply, and a pair of blood-red eyes, floating in midair, locked onto Cassius as he approached.

There was a bang, and the humanoid statue wobbled. The Slender Black Shadow pounced like a swift cheetah, its twisted claws emerging from the black mist and swiping down.

Bang!

For a moment, Cassius's right foot was nothing more than a blur. The shadow soared backward, crashing into and breaking the statue.

After rolling several times on the ground, it got back up as if nothing had happened. It darted around the room at high speed, bouncing off the corners like a refracted shadow.

Whoosh!

Dr. Tommy couldn't help but shout from where he was at the doorway, "Be careful!"

Behind Cassius, a shadow that had been crawling on the ground suddenly jumped up like a spring. With a leap, it threw itself onto his back with a thud. Hands spread out, it wrapped them tightly around Cassius's body, its head resting on his shoulder, close to his white neck.

"This…" Deputy Director Ole hesitated, looking at the old administrator beside him.

Ssss, ssss, ssss...

A sound like an electric current crackled intermittently, fading in and out, in the room. The Slender Black Shadow on Cassius's back arched its body as if it were inhaling and exhaling like a human.

That electric sound was coming from it.

This was how the Slender Black Shadow hunted. With every long suck, it extracted blood and essence from the human body, eventually leaving behind a shriveled, empty corpse.

Ssss, ssss, ssss...

The Slender Black Shadow was now very excited. It could feel this body's strength and the incredibly abundant energy within it. Sucking out this one person would be equivalent to hundreds of living humans.

So, the Slender Black Shadow doubled its efforts, its head making sucking motions as if it wanted to truly feast after five years of captivity. However, this body had incredibly tough skin, and extracting vitality seemed to require more time.

Thump, thump, thump! Thump! Thump, thump, thump! Thump…

Gradually, the two different heartbeats weaved together and merged. Cassius's breathing also became heavy and strange.

Without hesitating, he plopped down on the ground, crossed his legs, and activated the Golem Covert Martial Arts. The frequencies of his heartbeat, breathing, and blood circulation began to converge toward a single point. Since Cassius had tried this once before, it was much easier this time. The three frequencies gradually aligned and merged.

Buzz!!!

All at once, a weak but highly concentrated magnetic field—consisting of the Golem Breathing Technique, the miniature golem heart, and the three-dimensional map of the golem's vitality circulation—was born within Cassius and quickly spread out, instantly sweeping through his bones, muscles, and skin. It transmitted in a vibrating form into the body of the Slender Black Shadow behind him.

Suddenly, the shadowy figure began vibrating at the same frequency.

An unusual life magnetic field, different from that of ordinary creatures, was passively activated and released, forming its own frequency of vibration.

This uncontrolled vibration was enveloped by the faint golem magnetic field generated by the Golem Covert Martial Arts and was continuously transmitted into Cassius's body, first piercing through his skin, then his fascia, muscles, bones, and marrow. He could clearly feel his body calling out, like a parched sponge craving rainwater.

It feels like drinking sweet nectar… It's incredibly refreshing… Cassius couldn't help but moan inwardly.

If his activation of the Golem Breathing Technique to enhance his physique through the golem life magnetic field was like a small trickle of water, then the life magnetic field transmitted from the lanky shadow was like a flowing stream. Cassius could feel this stream enveloping every corner of his body, bringing a cool, refreshing sensation to his cells.

There was no other feeling except pure bliss. It was as if every part of his body was crying out, "We want more! More… more… more…"

Instinctively, Cassius increased the breathing rate of the Golem Breathing Technique, and the golem life magnetic field became even stronger.

The surging vibrations completely enveloped the lanky shadow, activating more of its foreign life magnetic fields. These fields then continuously transformed into vibrations, directing themselves into Cassius's body, and becoming delicious nourishment to enhance his life magnetic field.

"What the…"

Outside the door of cell No. 3, the four observers were utterly baffled. The lanky shadow had already latched onto Cassius's back, much like it had absorbed the blood and energy of other humans before. But strangely, the shadow's body was trembling like a sieve, not at all like it was enjoying a delicious meal. The black mist on its surface even seemed to be dispersing.

Especially in the last few seconds, the lanky shadow's entire body suddenly shook more violently, and it kept letting out painful hisses and roars. The mist on its body rapidly dissipated, the black color grew lighter, and it even began to take on a semi-transparent quality.

This situation was very bizarre.

It was as if…as if the lanky shadow hadn't absorbed anything from Cassius, but instead, it was Cassius who greedily sucked something out of it.

"Ah!"

Unleashing a shriek like that of a newborn, the lanky shadow tried to release its grip and distance itself from Cassius's body.

However, two hands had already reached over, firmly grasping those black claws. A tremendous force yanked down, pinning the upper body of the lanky shadow onto Cassius, preventing it from escaping. Meanwhile, the vibrating energy continued to pour into the shadow's body, stimulating and colliding with its life force field.

Screech, screech, screech!

A teeth-grinding scraping sound echoed across the floor. The lanky shadow's reverse-joint legs, like those of a leopard, clawed at the ground in a desperate attempt to retreat, but all it could do was leave behind white streaks of struggle. The power of this struggle was diminishing little by little.

As the mist spread widely, the shadow grew weaker and weaker. Eventually, the entire lanky shadow slumped limply on Cassius's back, twitching with each breath. It had lost all of its initial ferocity and now resembled a puddle of mud.

Hiss~

The last vibration was transmitted into Cassius's body.

The lanky shadow, as if it had completely lost its vitality, collapsed with a plop onto the ground, curling into a black shadow the size of a head. In the next moment, the shadow cracked and evaporated completely into mist.

Cassius opened his eyes slowly, a smile on his face. His body was drenched in sweat, but he felt incredibly refreshed.

A vibrant sense of vitality brewed deep within his flesh, lingering as if his internal organs and muscles were still basking in the previous afterglow, giving an illusion that they were still becoming more solid.

"As expected, using dark creatures for training yields unprecedented results." Cassius licked his lips and glanced at the upper right corner.

[Golem Covert Martial Arts: Physical Body 95.1% (Total Three Stages)]→ [Golem Covert Martial Arts: Physical Body 95.6% (Total Three Stages)]

An instant improvement of 0.5%. This was a 0.5% increase in the later stages of the first chapter of the Golem Covert Martial Arts, a level of difficulty similar to the later stages of the second chapter of the Wind Elephant Covert Martial Arts. If he were to train on his own, it would take at least several months, but now it only required fifteen minutes.

And the cost of such speedy progress was merely a single dark creature. He didn't know if there were other restrictions, but regardless, the Covert Martial Arts was undeniably strong and incredibly useful.

Cassius shot to his feet. Dr. Tommy involuntarily took two steps back, seemingly startled.

Nearby, Deputy Minister Ole muttered to himself, "It really worked. Such an incomprehensible way…"

Franz, the old administrator, glanced at Amos, who was frowning beside him. He took two steps closer, asking in a low voice, "Do you understand what just happened?"

"…" Amos merely shook his head.

Inside the room, Cassius stretched his body slightly, the joints all over his body cracking like popcorn. He looked at Amos, who was blocking the doorway, and said, "I can continue."

Amos flicked his hands, and the metal wires covering the entire doorway retracted, continuously winding back into the surface of his gloves. He glanced at Franz beside him. "Should we let him continue? The way he just disposed of the dark creature seemed…"

"Gruesome?" The old administrator shook his head, a weary smile appearing on his face. "As long as it's effective, there's no need to watch the process. Deputy Minister Ole, hand me the keys to the other eight cages. I want to see an executioner of dark creatures slowly execute these demons."

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