Chapter 1

SPLASH.

The sound of water can be heard.

SPLASH.

Hitting the rocks, then receding, spraying droplets, then receding, then hitting again.

A somehow soothing, primal sound. A monotonous, repeating grand chorus of nature.

SPLASH, SPLASH.

Hmm. Why am I hearing the sound of the sea?

SPLASH, SPLASH.

The water spray hitting my face is salty. A faint scent of the shore stings my nose, making my breath catch slightly.

My entire body aches terribly.

"...Ugh."

It's freezing.

Opening my eyes, I realized my face was pressed against rough rocks. I tried to raise myself by placing my hands on the wet rocks, but slipped on the moss and fell forward. My face hit hard and it hurts, plus every joint in my body is aching badly.

SPLASH.

"Bwah!"

An especially large wave came and slapped my face with full force.

As if receiving a baptism from the sea commanding me to wake up, I reluctantly decide to get up. It's high in salt, but it works as a face wash. The cold seawater has thoroughly washed away my drowsiness, so this time I carefully raise myself without slipping.

"...It's the sea."

An endless sea.

Dark waters surge forward, then recede. The waves that crash against the rocky shore where I'm sitting break into spray, and that's the water that's hitting my face.

I slowly stand up.

Is my whole body aching because I was sleeping on these rocks? Indeed, it feels similar to when I accidentally fell asleep on asphalt.

I twist my body as if to loosen up, and various parts make satisfying cracking sounds.

An endless sea. A rocky shore untouched by human hands.

Looking around the horizon, there are no ships, no human silhouettes, not even a buoy floating. Along the coastline, there seems to be a sandy beach, but it's certainly not a swimming area.

"...Where the hell is this place?"

Is this some kind of nasty prank?

That's what I think, but my memory is fuzzy. What was I doing before coming here?

I tried to recall my last memory, but my head throbbed painfully so I stopped. By the way, this is physical pain. I guess using a rock as a pillow wasn't a good idea.

Suddenly, light shines through. Looking up at the sky, clouds were drifting.

It seems to be nighttime now, and moonlight is visible.

And as the clouds parted, there were two moons.

"?"

What... does this mean?

Did the moon I know split in two? Or were there always two and I just didn't know about it? Has the true hidden form been revealed?

A red moon? Has the secrecy of the ritual been broken? Is the night of the beast hunt beginning?

My face, with mouth gaping open and staring blankly at the sky, must have looked quite foolish.

SPLASH. As if telling me to calm down, a large wave came and slapped my face with full force.

"...Huh?"

I don't understand.

Where am I? Who am I? Where are you now and what are you doing?

"An unfamiliar ceiling sky..."

Fortunately, it seems I still had enough mental capacity to make jokes.

"~ "

As I stood there, I suddenly heard a voice from behind.

A singing voice, perhaps. A strange sound, like humming, yet also like meaningful words coming through.

The low, calm melody was deeply soothing.

I turned around hurriedly.

Hoping that perhaps whoever was there might be the orchestrator, and wanting the big reveal of this elaborate prank.

"~~ "

There was a red woman.

Silver hair so long it reached her feet. A brilliant red outfit that made her look like a dancer.

From the zither in her hands came a melody that strangely resonated deep within my soul.

I knew this woman's name.

"Skadi the Corrupting Heart..."

Blood-red eyes pierced through me.

There's a game called Arknights.

Oripathy, an incurable and fatal disease. The Infected, those with Oripathy who become disease sources after death and are targets of discrimination. The Reunion Movement, an organization of the Infected. Rhodes Island, which aims to treat Oripathy and save more lives. The amnesiac protagonist and key figure, Doctor. Amiya, the "Demon King." The mature Kal'tsit. War breaks out as if saying "none of that matters."

The world of Terra is filled with gloom and misery, yet people live desperately for moments of fleeting brilliance.

The world of Terra can be roughly divided into two parts.

The land is nothing but trouble. The Infected are discriminated against, the weak are kicked down, life is cheap, and nations plotting war run rampant everywhere—it's definitely not a world I'd want to live in.

And what about the other part—the "Sea" is also a terrible place.

At the bottom of the sea lies the nation of Aegir, and since no other nations exist there, there's no war. Without exaggeration, Aegir's scientific prowess is the best in the world, and everyone is given work according to their abilities and can make a living.

Looking at just this aspect, it might seem like a wonderful paradise, but contrary to expectations, within Aegir—or rather, within the sea—terrifying monsters exist.

Beings called Seaborn, or "Gods," or This or That, are collectively known as sea monsters.

While the land-dwelling races fight amongst themselves, Aegir is engaged in a fierce war with these monsters.

By the way, it seems Aegir eventually suffers what amounts to defeat. And after conquering the sea, these sea monsters are said to come ashore and ravage the land.

On land, there are also many unknown monsters sleeping similar to the sea monsters, but it's unclear which side would win. Either way, probably no one will survive. Everyone's dead anyway.

This world is truly messed up!

Abyssal Hunters are a unit created by Aegir to counter the sea monsters. Of course, they don't have a normal origin; they're a group of superhumans created by utilizing the power of their enemies, the sea monsters.

With physical abilities far superior to most races of Terra, they pay the price of turning into sea monsters themselves if they overuse their power.

And Skadi is a member of these Abyssal Hunters. After various twists and turns, the Abyssal Hunters are annihilated but manage to kill the "God" at the apex of the monsters, but amusingly enough, the next "God" ends up dwelling within Skadi.

As long as Skadi's consciousness remains dominant, she can stay as a sword-wielding, socially awkward, powerhouse gorilla superhuman girl. But once the "God" dwelling within her awakens, Skadi's heart becomes corrupted and she turns into a vanguard of the sea. After that, the invasion of the land awaits.

It couldn't be worse.

And the woman singing before me was dressed like Skadi after her fall to darkness—that is, Skadi the Corrupting Heart.

"Um... is Skadi okay to call you?"

I nervously called out.

Before I could even think about why I was in such an incomprehensible situation, my body, instinctively sensing danger, moved on its own.

The woman opposite me:

"...Is that what you call me?"

It's the Corrupting Heart!

There's no way the real Skadi would tilt her head and make such a bizarre statement! I'm certain! This woman is a Seaborn monster, whether she's Ishar-mla or whatever!

I involuntarily clutched my head.

When I looked up at the sky, the two moons greeted me, making me feel extremely uncomfortable, so I glanced down, only to find Skadi (provisional) who had somehow approached and was peering up at me, causing me to let out a strange cry.

Actually, I fell over in surprise.

"You are... not one of my kind. But you are here. I wonder why?"

I don't know!

My constricted throat couldn't produce a shout, so I spat it out in my mind.

It's so incomprehensible that I could cry. I hit my butt hard when I fell and it really hurts. It's going to bruise.

...Wait, if Skadi the Corrupting Heart is here, does that mean the world of Terra hasn't been destroyed yet?

If I remember correctly, in the timeline where Skadi the Corrupting Heart appears, Rhodes is destroyed, Kal'tsit and Amiya are dead, and the only survivor is the Doctor. This is Skadi the Corrupting Heart trying to win over the Doctor, which is one of the most hopeless, terrible bad endings in the world of Terra.

The Doctor, the suspicious person in a black hood, is nowhere to be seen. Surely I'm not the Doctor... no, that can't be right. I don't know why I'm here, but I still have my memories.

However, if the world has indeed been destroyed, my future is also pitch-black.

"...Really now."

Skadi the Corrupting Heart—well, let's just call her Skadi—suddenly began singing. While staring at her somewhat glaring, I let out an involuntary sigh.

I look around.

The sea remains calm, with waves surging toward the rocks at my feet and breaking. Looking in all directions, there's no trace of artificial structures, but also no signs of conflict.

Come to think of it, there don't seem to be any Seaborn around. I'd probably be gobbled up in an instant, so that's a relief, but not knowing when they might appear is unsettling in its own way.

...Anyway, I should look for people.

I need to find shelter from the rain and wind, and I need to understand the situation. Also, where the hell am I? Iberia? I'm not familiar with Terra's geography. This is troubling.

In any case, the immediate problem is...

"What to do with this one..."

"~ "

Singing so carefree.

Since basic communication was established earlier, it's safe to assume we can understand each other. However, can one have a proper conversation with a sea monster, a Seaborn? According to the Doctor's description, they don't have blood flowing, and it's unclear if they can be killed even by strangulation.

I'll have to completely abandon the mindset of dealing with a human, but...

"I've never communicated with non-humans before."

At most, dogs or cats. Are Seaborn as friendly as dogs and cats...? No, I guess not...

Hopefully, the cheerfully singing Skadi has a tolerant and cooperative personality that shows understanding toward Lilin culture like a certain Kaworu-kun, but that would be helpful.

"~~ "

However, given that she's at the apex of monsters who are hostile to all other races in Terra, it's probably impossible...

"...I'm done for."

Looking up at the sky once more, the two moons were still looking down on me.

This is really tough.

And also, as I listened to Skadi's song, I felt the pain in my butt and throughout my body subsiding. That's right, she has a passive skill with regeneration...