Chapter 18
【Multi-Axis Burst Propulsion Organ】
＊A unique organ formed by the integration and mutation of the 「High-Speed Multi-Axis Propulsion Sac」, 「Sudden Acceleration Muscle」, and 「Current-Sensing Muscle」.
＊It senses the surrounding currents and automatically adjusts to the optimal direction of propulsion.
＊It generates explosive thrust through instantaneous muscle contractions and expansions, along with multi-axis mana jets.
＊The strain placed on the body during high-speed movement is reduced.
‘Just as I thought.’
It was exactly as the system had described the Multi-Axis Burst Propulsion Organ.
Through her tail, Nereia could sense how the surrounding currents changed.
Where whirlpools formed and where turbulent currents arose.
How she had to swing her tail to move in the direction she wanted.
How much thrust was generated based on the amount of mana she injected.
Nereia could instinctively understand all of it.
She didn’t need to consciously think about it.
She simply knew it by instinct.
Just as humans didn’t need to consciously think about breathing.
Just as humans could move their bodies as naturally as breathing.
That made the new organ she’d gained through Trait Organification feel just like a passive skill in a game.
Of course.
“I’ll need to get used to it, but that can’t be helped.”
Fwoom—!
Nereia gave her tail a light flick, and the immense thrust generated in an instant carried her dozens of meters in the blink of an eye.
If she hadn’t slowed down midway, she would have slammed straight into the canyon wall.
‘A little less force…’
Fwoom—!
The surrounding seawater was pushed aside as Nereia shot forward dozens of meters once more.
She wasn’t in danger of crashing into the canyon like before, but she still covered more distance than she’d expected.
Nereia thought, ‘As expected, you can’t get an exact sense of it just from reading about it.’
Still, though.
“This is pretty nice.”
Murmuring that with a grin, Nereia began to move in earnest.
She’d learned many times over that the best way to adapt to a changed body as quickly as possible was to move as much as she could.
Whooosh—!
Nereia cut through the seawater filling the deep-sea canyon as she surged forward.
Even though she wasn’t using much mana, she had long since surpassed the maximum speed of her old High-Speed Multi-Axis Propulsion Sac as she raced through the canyon.
She could also brake sharply and stop on a dime.
She could make 90- and 180-degree turns, move backward, ascend and descend vertically, spiral, slip between jagged rocks, or pass through gaps in the rocks by a hair’s breadth—all kinds of acrobatic movements.
Of course, she’d been capable of acrobatic movements before, but now she could perform them even more naturally.
The strain on her body during those movements was almost nonexistent.
She was also gradually gaining finer control over the mana used to generate thrust.
At this rate…
“I could swim all day.”
As Nereia swam about the canyon with that thought in mind, her tail sensed something.
Ahead and behind.
Left and right.
Above and below.
The currents, surging violently in no set direction, were more than familiar to Nereia.
And that was because…
“A turbulent current?”
Back when she’d been a deep-sea unicellular larva, she’d risked her life by diving into one to escape a deep-sea predatory larva.
The turbulent current in this deep-sea canyon was on an entirely different scale from the one she’d entered before.
It was the maw of a monster that swallowed everything. Once swept up and sucked inside, an entire body would be torn to shreds.
In particular, among the scraps of deep-sea creatures being swept around in the current were pieces of lesser predators.
“I think I can do it.”
Nereia glanced down at her tail and murmured.
With her tail, which could perfectly sense the flow of the surrounding currents and carry her in the optimal direction, she should be able to swim through the turbulent current before her.
It wasn’t arrogance, conceit, or even baseless confidence.
She simply felt it instinctively.
That she could move freely through that turbulent current as she was now.
So…
Fwoom—!
Nereia flicked her tail and plunged into the turbulent current.
* * *
“Aaaaaah—!”
Nereia screamed as she threw herself into the turbulent current.
But there wasn’t a trace of fear in her scream.
What colored her voice was elation, excitement, and joy.
And that was because…
“I-it’s like riding a roller coaster—!”
Nereia let herself be carried by the turbulent current’s wild, erratic flow and cried out in delight.
She surged forward, then suddenly dropped.
She plunged straight down, then shot back up in the opposite direction, banking sharply right one moment and left the next.
At times, an immense suction force tugged at her body.
The flow within the turbulent current made Nereia feel as though she were riding the roller coaster she’d gone on at an amusement park as a child.
Thanks to that, Nereia was able to experience pure joy for the first time in a long while.
How long had she swum through the turbulent current, riding it like an amusement park attraction?
A suction force from the left and a repulsive force from the right sent Nereia hurtling out of the current.
She did end up slamming into the canyon wall, but the blue-black outer shell that had grown even sturdier since her evolution into a Primitive Mutant Merfolk wasn’t even scratched.
“Whew, that was fun.”
Nereia crawled out from the canyon wall she’d crashed into and exclaimed with a delighted expression.
It really felt like she’d returned to her childhood for a little while.
Back in middle and high school, she’d been focused on studying. After becoming an adult, she’d become a deep-sea researcher, traveling only between the deep sea and the research institute. She’d never had a chance to experience this kind of fun.
Anyway…
“Where am I?”
Nereia said as she calmed down and looked around.
The turbulent current she’d plunged into had been enormous.
It was beyond comparison with the one she’d entered as a deep-sea unicellular larva—so huge that she couldn’t help wondering if it stretched for dozens of kilometers.
That was why it had sent her flying out in a completely different place from where she’d first entered the current.
Having arrived in a new place, Nereia looked around and couldn’t help letting out an exclamation of admiration.
“Wow—.”
What met Nereia’s eyes was a vast ecosystem formed by countless deep-sea creatures gathered together.
A deep-sea fish with a transparent body through which all its internal organs were visible.
A deep-sea creature that stored compressed water and sprayed it out when danger approached.
A giant squid that changed from moment to moment, blending into its surroundings.
A giant worm that used the enormous electrical current generated by the hundreds of tentacles sprouting from its body to stun its prey before swallowing it whole, and more.
As she gazed at all the deep-sea creatures she’d never seen before, Nereia wiped the drool from her mouth and said,
“I want to try eating them.”
She wasn’t curious about the taste.
Even after evolving into a Primitive Mutant Merfolk, she still hadn’t developed a sense of taste.
There was only one reason Nereia wanted to eat them.
If she ate them…
“What new traits could I gain?”
Nereia was wiping the drool from her mouth and murmuring when it happened.
Flutter, flutter.
A jellyfish drifted past Nereia, moving its wavering body.
As the jellyfish, with its translucent body and dozens of tentacles, passed by her, Nereia swung her hand.
Whoosh—!
Her hand swept smoothly through the deep-sea water, and just as it was about to touch the jellyfish…
Crackle—!
A faint mana reaction flared from the jellyfish’s body for an instant, and…
Swoosh—!
Nereia’s swinging hand cut through empty water.
“What…?”
Nereia cried out in confusion as the jellyfish vanished before her eyes in an instant.
It wasn’t a matter of being fast or slow.
It had literally disappeared right in front of her in an instant, as if it had leapt from one space to another.
Confused, Nereia scanned her surroundings and spotted the jellyfish swimming not far away.
Watching it drift gracefully with the deep-sea currents, as if teasing her, Nereia grinned.
Fine.
“You’re my first prey.”
As Nereia murmured those words, her back split open, and…
Crack! Crack!
With a strange, chilling sound, eight tentacles emerged from the opening in her back.
They were what had been called the Multi-Erosion Predation Arms back when she was a Deep-Sea Mutant Predator.
Now that she’d become a Primitive Mutant Merfolk, they were called…
【Dorsal Eightfold Predation Tentacles】
＊Eight tentacle-like auxiliary organs stored in her back.
＊Each tentacle moves independently and assists with various activities, including capturing, restraining, and attacking.
＊Acidic fluid can be released from the sharp protrusions at the tips of the tentacles.
＊The mouths at the tips of the tentacles can devour targets.
They were one of Nereia’s auxiliary organs, used for predation.
Moving the eight tentacles that had emerged from the opening in her back, Nereia murmured,
“I’ll gladly feast on those new traits.”.
“I’ll gladly feast on those new traits.”