The World Tree of Earth
In a dazed state, I stood behind the being with arms sprouting from its back, waiting my turn. When it came, I stepped into the machine. A moving platform on the floor carried me forward even as I stood still.
‘Infrared, laser, ultrasound, unknown wavelengths… all kinds of sensors are scanning my entire body.’
‘This feels like some kind of immigration checkpoint.’
‘It must be managing entry for beings from countless dimensions. They can’t allow dangerous entities or items through.’
‘Hmm.’
After passing through the machine, the atmosphere among the officers grew strange as they examined the results on their screens. The woman with animal ears frowned as though dealing with a nuisance, exchanged words with the multi-eyed being beside her, then gestured at me and called out.
“You there, robot. Come here.”
“Excuse me? Me?”
“Is there another robot here besides you? Hurry up.”
They seemed to have mistaken my full-body prosthesis for a robot. When I stood before her desk, she looked up from her computer.
“An unregistered robot? Who is your owner?”
“I’m not a robot. I simply possess a full-body prosthesis.”
“Don’t you know the law? If more than eighty percent of your body is non-biological, you’re classified as a robot.”
“I… see.”
How would I know the laws of this dimension? Flustered and unsure what to do, I was saved by Ruya, who had just emerged from the machine behind me.
“Hello, Moua.”
“Oh my, hello, Agracil.”
Her irritated expression melted away instantly as she greeted Ruya warmly. While I marveled at the lightning-fast change in demeanor, the two continued their conversation.
“This person is a dimensional lost child we found in a dungeon. I’ve agreed to be her guardian.”
“A person? From what I can see, that’s a robot with over eighty percent non-biological components.”
Ruya tried to hide her bewilderment as she glanced at me, then pressed on.
“There are circumstances that are difficult to explain. What matters is that she comes from a new dimension and is protected under dimensional law. I can vouch for her.”
“If you’re vouching for her, Agracil, then I can trust it. I’ll process it that way.”
“Thank you for your consideration.”
After finishing the paperwork with a bright smile, Ruya and I walked through the building together. The structure felt eerily similar to those in Eden—familiar yet foreign at the same time. The gray-and-white walls and floors, the angular furniture and fixtures, all echoed Eden’s aesthetic.
‘It really is similar to Eden. Of course, unlike Eden, which was populated only by humans, this place has an incredible variety of species.’
‘Look at that person walking over there—their skin looks reptilian, but their face is human.’
‘What about that slime-like being over there?’
A massive, amorphous slime-like entity was pulling a loaded cart, its round, face-like core shifting inside its translucent body. It even wore what looked like a hat on the protrusion atop its head. There was also a giant bird-like creature with black feathered wings and a red beak, and an insectoid being walking upright in full clothing.
‘At this point, a succubus probably doesn’t even rank as particularly unusual.’
‘A succubus carrying a full-body prosthesis, Abaddon, and an AI all in one body would still stand out.’
As I kept turning my head to stare at the strange beings, Ruya, walking beside me, chuckled softly.
“That fascinating?”
“Where I lived, the only intelligent beings were humans and a few others. This is all incredibly new to me. Still, the buildings and clothing feel similar to what I’m used to.”
“Speaking of that—how advanced was the civilization in your dimension?”
“Civilization level?”
I wasn’t sure what exactly she meant.
“Roughly speaking, we divide them into primitive civilizations with little scientific development, scientific civilizations with notable achievements in communication and energy, spacefaring civilizations that have reached the stars, and dimensional civilizations capable of interfering with other dimensions. This Earth dimension, for example, is at the dimensional level.”
“The criteria seem rather vague.”
“With so many civilizations across countless dimensions, clear divisions are difficult. Still, these four categories are the easiest to work with.”
“Hmm.”
The dimension I came from had enormous technological gaps between regions. Remote villages lived like they were in the countryside, while major cities were cutting-edge scientific metropolises. Since most of the population lived in cities or border towns, it probably counted as a scientific civilization.
“I suppose it would be a scientific civilization.”
“A civilization capable of creating cyborgs never made it to space?”
“Even though my body is a full prosthesis, it isn’t exactly a cyborg. Besides, there were many flying monsters where I lived. It was too dangerous to develop aerial travel.”
“So you haven’t conquered monsters yet? Ah, never mind. Let’s hurry and get you registered first.”
Following Ruya’s urging, we stepped out of the building—and the sight outside was far more overwhelming than what I had seen within. Towering buildings bathed in sunlight stretched into the sky, with cars flying between them and countless winged beings soaring through the air. Other creatures swam along waterways carved into the streets, while blue-and-white robots moved freely about. Buildings stood in dense clusters everywhere, like a forest of structures. Above it all, lush green leaves filled the sky.
In front of the building was a wide, clean plaza where various beings lined up to board floating cars rising and descending through the air. Ruya led me to one that had just landed. The vehicle had no driver; it took off automatically, flying toward some unknown destination.
The view of the metropolis outside the window was breathtaking.
‘Incredible! Even floating cars back home couldn’t fly this high. These cars are actually soaring through the sky!’
‘How are they flying?’
‘It doesn’t look like conventional propulsion. Could it be magic?’
While we were distracted by the scenery, Ruya finished a call and turned to me.
“Gwangnam and the others went off to handle their own matters. We’re heading straight to the Dimensional Management Bureau to file your lost-child application.”
“Understood.”
“Once you’re registered as a lost child, there will be a detailed investigation into the dimension you came from. You’ll just need to cooperate during that process.”
She smiled, then operated a panel on the window, rendering the sides and ceiling transparent.
“Welcome to Earth, the crossroads of dimensions.”
“Wow~”
The view was far more majestic than anything seen through a regular window. The forest of towering buildings made even the most advanced parts of Eden seem insignificant. But what truly captured the eye was the unimaginably massive tree standing at the center of it all.
“How can a tree grow to that size…?”
‘It’s awe-inspiring.’
The colossal tree radiated vigorous life force. Water cascaded down its trunk like waterfalls in places, and countless winged beings flew around it. Its vast canopy of blue-green leaves swayed in the wind like waves. The tree was so enormous that low-hanging clouds brushed against its upper branches.
While we stared, captivated, Ruya spoke with pride in her voice.
“That’s the World Tree, the pride of us elves. Hundreds of years ago, when the elves migrated to Earth, they planted a World Tree seed in Korean soil. It grew into what you see now.”
“It’s truly magnificent. Has it reached full maturity?”
“I heard it’s still growing. The original World Tree in our home dimension was supposedly much larger.”
“Wow…”
“The World Tree accelerates and purifies the circulation of mana and spirit energy between land and sky. Thanks to the immense amount of purified mana and spirit energy it emits, not only spirits but all living beings can maintain healthy bodies simply by being near it.”
Ruya’s pride in the World Tree was evident—likely because she was an elf. According to her, the World Tree’s role as the world’s purifier made it indispensable to elves, beings of nature. Elves needed places rich in spirit energy to grow and thrive, so the World Tree’s existence was inseparable from their own.
“Try using your vital energy to look around the World Tree.”
Following her suggestion, I gathered vital energy into my eyes—and an even more astonishing sight unfolded. Countless spirits of all shapes, sizes, and colors drifted leisurely through the air around the massive World Tree or perched upon its branches. There were so many that the sheer number made my head spin.
“I can’t find words beyond simple awe.”
“Beautiful, isn’t it? This is a sight unique to the World Tree in Korea—the only one on Earth. Photographs of the World Tree taken by spirit mages are famous as some of the most beautiful images on the planet.”
“I’ve never seen anything like this before.”
It was my first time seeing spirits in person, let alone so many at once. But something puzzled me.
“Elves, succubi… the range of beings considered spirits seems broader than I thought.”
“Elves and succubi are both broadly classified as material-realm spirits. The ones flying around the World Tree are nature spirits. The biggest difference is whether they possess a physical body or not. Nature spirits can survive on spirit energy alone, while material spirits require more.”
“So material spirits are beings that need spirit energy and possess physical bodies.”
“Exactly. We elves must absorb sufficient spirit energy and store it within our bodies to grow. We have a core in the center of our chest, beside the heart, that gathers spirit energy. Do succubi have something similar?”
“Succubi have a core that accumulates vital energy in the womb.”
Ruya’s expression went blank for a moment, then flushed slightly as she gave an awkward laugh.
“Huh? Where did you say? Did I mishear?”
“A core that gathers vital energy in the womb.”
“Th-that’s… well. I suppose that makes sense for succubi, but a core in the womb is a little surprising.”
For some reason, she seemed more embarrassed than I was. After clearing her throat, she asked with sparkling eyes.
“So, is the core in the womb meant to make absorbing vital energy easier?”
“Probably. It’s also a symbolic organ of femininity.”
“And is sexual intercourse with males the best way to absorb vital energy?”
“It’s possible to absorb from females too, but it’s more efficient with males.”
“There are legends about succubi that say they make it easier to seduce males. Is that true?”
Make it easier to seduce males? Did she mean making women more alluring to men?
‘From the look on her face, she must have a man she wants to seduce.’
‘Probably. But is there a way to do that?’
‘The Yin Brand only affects the one it’s engraved on, but ovarian modification would make the body emit pheromones that attract the opposite sex. That’s probably the only relevant effect.’
‘Still, we can’t just perform ovarian modification on Ruya.’
Even though ovarian modification enhanced feminine functions and added pheromone-based seduction effects, it also came with significant side effects like inducing estrus. It wasn’t something to perform lightly on just anyone.
‘If we explain it to her and she consents, it should be fine. It’s not harmful to the body, and since she’s the woman who will become our guardian in this world, it would be good to repay her kindness by engraving the Yin Brand as well and bringing her under our influence.’
‘Bringing her under our influence… is that really necessary?’
‘Remember how that animal-eared woman at the gate station immediately offered assistance after hearing Ruya’s family name? Ruya might belong to a far more prestigious and influential family than we realize. For us, who will soon face a powerful unknown dimension head-on, her support could be invaluable.’
Elisa’s words made sense. Someone who could freely manipulate dimensional gates and belonged to this highly advanced civilization would be an essential ally. I looked at Ruya again as she waited for my answer. Her flowing, beautiful light-green hair, her lively flushed cheeks, and her lovely features matched Elisa’s preferences perfectly.
‘The real reason is that she’s a female you find appealing, isn’t it?’
‘You’re quite perceptive, miss.’
‘Hehe, I like her too. Being an elf spirit, she’s rich in vital energy.’
Perhaps because we were near the World Tree, overflowing with spirit energy, Ruya radiated abundant life force and carried a great deal of vital energy. If we were going to stay here for a while, we would need a stable source of vital energy—and she was the perfect candidate.