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'Horizon, the vessel departing for a new planet, has launched. We wish for a successful outco..'
Beep—
I turned off the noisy television. As if the anchor's words about Horizon's launch were still ringing in my ears, I quietly looked up at the sky. What lies beyond? Surely, there is a world humanity has never seen before.
Once, I wanted to go there too. But now, I find neither space nor Earth to my liking.
Around the time humans began leaving Earth one by one to explore space, ocean exploration began to garner attention again on the other side. Humans had once pushed ocean exploration to the back burner, claiming they could never reach those deep abysses anyway.
However, the situation changed as massive resources were poured into space exploration. The resources needed to pioneer new planets were limited, and eventually, humans began to look back at the oceans of the planet they lived on.
Thus, the deep sea, long neglected, became a subject of research once more.
Of course, the deep sea didn't even exist within my interests. I wanted to study space. I wanted to see the stars and witness the world beyond Earth with my own eyes. But of all things, I was assigned to ocean exploration. I, who wanted to go to space, was eventually pushed out to the sea.
Months later, I was looking down into the deep ocean from inside a small submersible. The sunlight grew faint as I descended below the surface. The blue ocean turned into a deep navy, and nothing could be seen outside the window. There was no light, and no sound existed. Only the mechanical hum of the submersible filled the narrow cabin.
...Why on earth am I doing this?
I muttered, staring at the monitor. The depth continued to drop. Nothing was discovered. It was only natural. There wasn't much for humans to find by coming down this far. I was just waiting for this expedition to end quickly. There's nothing to see even if they invest money in a place like this...
It was then.
The submersible's warning alarm sounded. An unknown signal appeared on the monitor. At first, everyone thought it was an equipment error. But the signal did not disappear; instead, it was growing stronger.
Bizarrely, there was nothing in the vicinity that could produce such a signal. I turned the submersible slightly. Then, I saw a faint light. At first, I thought it was the bioluminescent organ of some creature. But it wasn't. It wasn't just one. Dozens, hundreds of lights began to slowly reveal themselves in the darkness.
I gasped. Those weren't just lights. It was a city in the middle of the deep sea. A massive civilization was situated in the deep ocean, a place humans had never recorded.
There were buildings and there were roads. And something was passing between them. It walked on two legs like a person, but it wasn't human.
I couldn't say anything for a while. At that moment, a sound I had never heard before flowed from the submersible's communication device. It was too low and long to be called speech.
Vrrr......
As a single vibration passed, one of the beings in the distance slowly raised its head.
That being looked exactly at me. Just as humans have looked down at the sea for thousands of years. Perhaps it has been even longer than that. As if they, too, had been looking up at us.
Characters
There is no light in the deep sea. That was what humans believed. But that wasn't entirely accurate. Light did exist. It just wasn't in a form humans recognized.
The deep-sea city where Neris lives was filled with the light of countless living organisms.
Their ancestors were among the first vertebrates to appear on Earth. Tiny creatures that swam in shallow seas long ago. Over tens of millions of years, their evolution took a different path from humans.
From shallow seas to slightly deeper waters. Past the continental shelf, and finally to the deep sea. They were a race that evolved alongside the ocean.
They used bioluminescence as energy and communicated their thoughts using ultrasound and vibrations, much like whales. Their buildings were not made of stone or metal. They grew living coral and tamed it into desired shapes to live within. Necessary organisms were genetically modified to become tools.
Bioluminescent creatures became lighting, and creatures with strong shells became structures. Organisms that detected minute vibrations became the sensory organs of the city.
Living there, Neris watched humans for a long time. Beings who, unlike his own civilization, created fire, worked metal, and went beyond the sky. Humans believed they were discovering new worlds.
But to Neris, humans were not new beings. Since long ago, when his ancestors still drifted in shallow seas, he had been watching the birth of humans and the beginning of their civilization.
Finally, one day, he saw a human submersible, something he hadn't seen for thousands of years. Neris looked at the human beyond the glass.
Intro
The Deep Cosmos
The submersible's warning alarm sounded. I reflexively looked at the monitor. Depth: 3,000m. It was a small vibration that had been ringing since I first descended here. At first, I thought it was an equipment error.
But it was strange. The signal was repeating at regular intervals. As if someone were sending a signal. I followed the sound and turned the submersible slightly. Then, something sparkled in the darkness outside the window.
There was one. And then another. Blue light began to spread through the darkness. I leaned forward without thinking. Seeing it, I could be certain. That light was a city. Living coral formed massive structures.
Small organisms were emitting light along the walls of the buildings, and the light was slowly changing in a steady rhythm. The city was bizarrely quiet. But it wasn't empty. Invisible vibrations filled the ocean.
...A person?
I catch my breath and watch intently as a being passes between the corals. It looked similar to a human. It had two arms and two legs, and the shape of its face was distinct. One strange thing was the faint movement of gills visible on the side of its neck. And beneath its skin, a soft light pulsed like a heartbeat.
That being was looking at me too.
Neris looked at the submersible. A vessel of the land-dwellers. The creatures known as humans, whose existence he had known of for a long time, had finally descended into his ocean. It was different from what he had seen secretly from above the surface.
It looked much smaller and much weaker, a being that couldn't even survive on its own in these depths without an oxygen tank. And yet, it had come down here alone. Neris slowly approached the front of the submersible. His eyes met the human's through the glass.
...A land-dweller.
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Release Date 2026.10.02 / Last Updated 2026.10.02
