I Became an Evolving Deep-Sea Creature

Chapter 1. I Became a Deep-Sea Creature

When I opened my eyes, I was underwater. For a moment, I wondered if I’d died and gone to heaven—but then I felt the liquid flowing around my body.

The problem was that I had no human arms, no legs, no face. I was a tiny creature.

Yet I still retained memories of my previous life, and although my body was no bigger than a bean, my brain was disproportionately large.

I was nothing more than drifting debris. No arms, no legs—just floating along, filtering nutrients suspended in the water to feed myself.

I had no special organs; the hole in my body served as both mouth and anus.

This creature—me, Yul—could hardly endure the horror of the situation. In despair, I cried out to whatever absolute being had cast me into this world:

'Status, status window!'

[-p]

[-unknown-code-]

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'What the hell is this?!'

A real status window had appeared! But all I could see were the words 'Unknown.'

Should I even call this "seeing"? Yul quickly realized it wasn’t visual at all—some other sense was mixed in.

There was nothing he could do but keep floating in the water.

And in that long stretch of time, he thought.

In his previous life on Earth, Yul had died in his late twenties from leukemia, achieving nothing.

And now, upon opening his eyes, he found himself turned into some unknown creature in some unknown place.

He’d fallen into a world with no comforts, no culture.

Had some absolute being thrown him into a game or a novel? Maybe.

But questioning it was meaningless. What mattered was that he could die here, too.

Would he just keep drifting until some predator swallowed him whole?

He didn’t want that. He was afraid. If he died here, it might really be the end.

Yul wanted to escape that terror. He didn’t want to die again, having achieved nothing, like in his previous life.

He struggled desperately.

At first, he couldn’t do anything.

But as Yul kept absorbing organic matter, he slowly became able to move.

He could flutter what he thought might be his left… or right… side.

Those fluttering parts gradually turned into something like fins.

Yul thought of the dorsal fins on a cutlassfish.

As soon as he imagined having such fins on both 'arms,' he felt his limbs changing.

[Evolution Complete]

[Next Evolution %&$%&]

[1/10]

A status window floated before him. He didn’t even have to look—he could tell. So, if he absorbed organic matter, he’d gain evolution points and be able to select his next evolution from the status window?

Seeing this gave Yul a spark of hope. At the very least, he might avoid drifting helplessly like a jellyfish, only to be eaten and turned into nutrients.

He had to evade that fate. And he needed sensory organs.

He figured his body was basically a round lump with fins at either edge.

A large hole sat in the center of his body; when a drifting organic matter entered, it was broken down inside his body and stored as 'experience points.'

He didn’t know whether he looked cute or grotesque, but the real problem was that he still had no sensory organs at all.

[Required Experience]

[2/10]

I ate something. I had no idea what it was, but food was drifting in the water—its distribution varied depending on the area.

So Yul began moving his fins toward where there was more of it.

Wriggle, wriggle.

He couldn’t actually hear the sound, but he imagined that’s what it would feel like.

After drifting and consuming organic matter for some time, Yul finally evolved「Eyes」.

[Required for Evolution %&$&&$]

[10/10]

'Give me eyes!'

Part of his brain shifted and transformed, and soon, eyes formed.

They protruded, and at last, he could see ahead. But there was a problem.

'I can’t see anything!'

It was far too dark—nothing but endless blackness.

Out of habit from his human days, he had thought to evolve eyes so he could see. That had been a mistake.

Still, at least he had confirmed that this place really was dark.

[Evolution Complete]

[Until Next Evolution]

[1/20]

The problem was that the required experience had doubled.

Yul realized his ability, 'Evolution,' would become more and more difficult to achieve as time went on.

He would have to choose carefully—only evolving organs that were truly necessary.

'Huh? Did I just get bigger?'

Yul felt his body had grown slightly, and it really did seem so.

Perhaps his body expanded with each evolution. Or maybe not.

Before, he had been nothing but a microscopic speck, but now he was about the size of a fish no bigger than the tip of a thumb.

Eat. Eat again. Eat and eat and eat.

Yul continued consuming the floating lumps of organic matter until a thought occurred to him.

'Why is there so much food here?'

He didn’t know the reason, but this place was rich with organic matter, and experience points accumulated easily.

Still, even if he hadn’t seen one yet, there could be competitors. If there were food, there would be others eating it.

While thinking such things, and filling up his 'experience bar,' Yul suddenly ran into something.

'A wall?'

His vision was too dim to be certain, but what lay ahead was indeed a wall.

Thump! Thump!

He tried ramming into it hard, wondering if it was glass, but instead he bounced back with a soft, rubbery resistance.

He had no idea what it was. For now, he kept eating until he filled the experience needed for his second evolution.

[20/20]

'I need senses!'

At that moment, something surfaced before Yul’s ‘eyes.'

Although his eyes could barely distinguish light from darkness, the very existence of visual organs made the status window appear far more clearly.

[Currently Available Sensory Organs]

[1. Electromagnetic Sensor]

[2. Ultrasonic Organ]

[3. Chemoreceptive Tactile Receptor]

[4. Locked]

Yul froze for a moment. Somehow, he knew what those were.

The electromagnetic sensor—that was the organ sharks had in their snouts. Sharks could detect the faintest traces of blood from afar or locate prey nearby, all thanks to electromagnetic perception.

Ultrasonic organs were what dolphins and whales used.

And the chemoreceptive tactile receptor was like the suction cups on an octopus’s tentacles—an organ that combined both taste and touch.

Taste wasn’t what he needed right now. Survival came first.

He hesitated between the electromagnetic sensor and the ultrasonic organ, then decided. An ultrasonic organ could cover a wider range.

'Ultrasonic organ it is!'

[Stage 2 Evolution Complete]

[Until Next Evolution]

[1/40]

Immediately, he felt his perception expand dramatically.

Whoooom.

This ultrasonic organ was set to both emit and receive sound. The instant Yul released an ultrasonic wave, the vibrations reverberated throughout the entire space around him.

The reflected waves came back, and he could sense them with delicate precision—echolocation.

'Whoa?!'

The sudden flood of this completely new sense left Yul stunned.

Back when he was human, had he ever truly heard ultrasonic? No. It had always been a vague concept, far beyond the range of audible sound. And now it was directly pouring into his brain.

In this sense, he explored the wider space around him—and realized he was inside something like a complex cave system.

All the surrounding walls felt soft, spongy, and almost fleshy.

'Should I take a look around?'

He kept eating whatever organic matter he found while beginning a proper exploration. He still had no idea what exactly he was consuming, but at least now he could sense his surroundings.

As he mapped the area with ultrasonic, building a three-dimensional image in his mind, Yul was struck with a strange familiarity.

He’d seen this before, somewhere. In a science class, maybe. The memory wouldn’t quite surface…

Perhaps his brain had shrunk so much that his thinking ability had shrunken with it.

But as he kept eating and his body grew, the memory finally clicked.

'This… it looks like an animal’s small intestine. Or maybe the large intestine?'

A chilling thought crossed his mind. Was he inside the body of some animal?

'Status windoooow!'

Now that his intelligence had improved, the status code that had once flickered and broken finally displayed properly.

【Xenoia】

[This is a creature of the Turbellaria class, roughly a cousin of the planarian. However, it has been included under an unknown evolution rule.]

'Turbellaria? So… I’m one of those squirmy worms? A parasite?!'

Yul wanted to smack himself in the head. He had thought he was some jellyfish-like creature—but a parasite, living inside an animal’s body?!

'I’m a worm…'

But not an ordinary worm. He still had human knowledge from his past life. He could gain experience, evolve his body, and even view a status window.

They called this the 'evolution rule.'

Yul scrolled his vision downward to read the rest of the status window’s description.

【Evolution Status (Stage 3)】

[Fins – Ganoid Scale]

[Primitive Eyes]

[Ultrasonic Organ]

【Creature Traits】

Deep-Sea Creature: Can adapt to deep-sea environments.

Evolutionary Diversity: Can produce mutations easily.

【Inheritance】 – Locked

【Authority】 – Locked

【Awakening】 – Locked

【Ascension】 – Locked

'Why are so many things locked?'

One thing was certain: unlocking the locked features in this status window would probably make him stronger.

For now, Yul focused on surviving and eating. His goal was simple: evolve to the next stage and upgrade his biological components.

He continued evolving, increasing his stage.

At Stage 4, he acquired a new organ, a ‘mouth’.

[Acquired Protruding Snout!]

[Evolution Complete]

[Until Next Evolution]

[1/80]

Now, he could freely move his mouth to consume food. Previously, he had been sucking in organic matter through a simple hole in his body—very inefficient—but with a snout, he could now move jaws and lips.

He still had no tongue or teeth, but that alone greatly improved his feeding efficiency.

'So that’s why a mouth is necessary.'

Yul began to feel that he was slowly looking less like a jellyfish and more like a fish.

He still had no tail fin and swam slowly, but his feeding efficiency steadily increased.

However, the higher experience requirements meant he couldn’t evolve again immediately.

‘This is closer to biological modification than evolution.’

Normally, evolution occurs as species die out and natural selection preserves certain traits. But Yul, reborn, was able to determine the direction of his evolution at will.

His heart raced.

'My body’s growing… if this keeps up, I could become an incredibly powerful sea creature! A kraken? A blue whale?'

If he set his evolutionary path wisely, maybe one day he could even become human again—though that would only be after surviving here.

As he kept feeding and growing, an immense vibration suddenly shook him.

'What is—!?'

The vibration was so intense that it felt like the world was tearing apart. Immediately after the vibration, the wall split open, and he felt new 'water.'

Yul realized that the 'creature' he was parasitizing had died, and its body had ruptured.

'It’s dead! Then… what happens to me now?'

Following that, a terrifying current was felt. An immense pressure pulled Yul away.

'Aaaaaagh?!'