Planet Earth - Core

-[ Many many thousands years ago ]-

In the deepest place of the world, literally at the core of the Earth. there is a hollow dark void that doesn't even have gravity let alone any basic living principles like oxygen or water. Not even light existed there.

It was a true void that is not that much different from outer space. Only that this one was inside a planet. And also it was extremely hot. Instead of the freezing cold you normally find in the vast universe.

As much as outrageous that sounds, it really is the truth.

"..."

And in such a horrifying place, a single being existed. After he created the void, the being just stood in his place for almost 500 years now. He didn't even move a single muscle the entire time. Taking all that time planning in his terrifying mind what might be probably the most complex, biggest and powerful machine in the history of the world.

He was trying to take advantage of his advanced alien knowledge and develop an unholy machine that would be capable of defying space and time that will create a massive dimension with a different time scale that will also have to coexist with this dimension at the same time.

All the other Gods took the easiest path and just claimed one of the many pocket dimensions that branches of this universe and simply developed their world there.

However, this being refuses to do it. After all branches are just that... branches. No matter how big or robust those branches are, in the end they are simply low-level dimensions that depend on this one. Who knows what kind of complications and limitations he will face there in the long run.

So the being decided that he will not risk it, and will instead do the impossible and make a new dimension and then somehow force it to coexist with this one.

And after another 900 years, he finally did it. He completed the unholy machine that defied the laws of the universe.

*LOOOM*

As he looked at the finished project, now all that was left was an energy source to power it.

However, such an unholy machine would require so much power that even if you give it a thousand stars like the sun it still won't be enough. Not even close.

Fortunately, while he was training in the universe, the being came across a hypergiant star with a radius around 1,700 times larger than the radius of the sun. To put that in perspective, the volume of almost 5 billion suns could fit inside a sphere of that hypergiant star. That was more than enough energy for the unholy machine.

But first he needs to somehow compress it. Moreover, he has to do it far away in the empty corners of the universe.

Because if he did here, the moment he got the hypergiant star out from his inventory… this solar system will disappear.

-[ Timeskip: 10 year ]-

It took way more than he thought to compress the hypergiant star. He had to use his telekinesis powers constantly and slowly to make sure the compressed star was stable.

The originally 2.3765 billion km in diameter hypergiant star was now a white ball no more than 14.4 cm in size. The sheer power that seemingly small object has is enough to erase the Milky Way galaxy entirely from existence in an instant. It is now easily considered one of the most dangerous objects in the world.

The being however handled such a terrifying thing like a harmless sack of potato. He just casually carried it under his arm and teleported back to the void.

-[ Timeskip: 2 years ]-

It took some time to calibrate the machine with the compressed star. But now, it is done.

*Clack* *Crackle*

The unholy machine slowly came to live as the untold structures and alien technology started rotating. The speed gradually increased and before long it already broke the speed of light.

At that moment, the being completed his first step.

-[ Timeskip: 1000 years ]-

An entire basic ecosystem was completed. The void now became a massive dimension and a habitable zone with huge oceans and large continents of continuous expanses of land.

The being created some fast growing plant seeds and highly mutable bacteria from scratch and then released them into his world.

-[ Timeskip: 50,000 years ]-

The basic ecosystem evolved. It has become a perfect geographic area where plants, animals, and other unknown organisms, as well as weather and landscape, work together to form a bubble of life.

"..."

The being looked at the result and nodded.

-[ Timeskip: 700 years ]-

The being finished building his antimatter tower. It was the biggest building and the strongest structure in the entire world.

He now began experimenting with living organisms.

-[ Timeskip: 1000 years ]-

"Boga?"

"..."

The being succeeded in creating a humanoid intelligent creature. He unsurprisingly named it 'Human'.

He made a female counterpart for it and taught them how to survive in his world.

They hunt animals for meat and fight the unknown organisms to survive.

-[ Timeskip: 100,000 years ]-

*Roar*

"Boga! Gazeu!"

"Tina!"

*Bonk*

"Taja! Taja! Phew…"

The humans still live in The Stone Age and used the same primitive stone tools he taught them how to make.

The unknown organisms proved to be too strong even for the superhumans, they are almost at the bottom of the food chain and are constantly under the threat of extinction.

If not for the genetic physical upgrade he gave them over the surface's normal humans, they would have already gone extinct long ago.

At this rate it will take millions of years before they even progress to the next Age.

"?"

The being noticed that while he was frustrated, his Ki was unconsciously leaking and already spread throughout the entire dimension.

It is highly diluted but is still saturated enough to be used by these humans.

He chose a random pregnant female and gave her child's Ki the same wavelength as that dilated Ki.

-[ Timeskip: 50 years ]-

"Ajji Majji la Tarajji!" *Baam*

The first 'Magician' in history was born.

The humans called the diluted Ki 'The World's Mana'.

-[ Timeskip: 500,000 years ]-

"Long live The Lord!"

"Ohhh, kami…"

"My Lord, please forgive this sinful king."

"Shall the Lord bless this unfortunate child's soul."

The humanoid intelligent creatures built a civilization. At some point in time, they started calling him 'The Lord'. He just accepted it with a shrug.

They are stagnant at medieval level.

To boost their civilization, the being injected the unknown organisms with various cores of diluted Ki and threw them into countless underground structures he built all over the world.

The humans called them 'Magic Stones' and 'Dungeons' respectively.

And called the mutated unknown organisms 'Monsters'.

He also placed a miniature alien machine in each of those underground structures's lowest level to respawn the dead mutated unknown organisms indefinitely.

They called that machine 'Dungeon's Core'.

Some mutated unknown organisms evolved and started dropping random items. And the alien machine also glitched from time to time and spawned powerful magical objects in hidden places of the underground structures. It was an unexpected outcome but a welcomed one by the creatures nonetheless so the being didn't interfere to fix it.

The humans called them 'Drop Items', and 'Dungeon Treasures' respectively.

-[ Timeskip: 2000 years ]-

Despite his change to the world and the many 'Magical Items' they developed using the Magic Stones, except of some quality of life and comfort improvement… their civilization is still stuck at medieval level.

Mainly because there is a lack of wars. His presence prevents drastic internal conflict.

Peace is the bane of progress and pain brings change. So he secretly created a nemesis for them.

The being called it 'The Demon King'. It was humanoid, almost like a human. But has purple horns and slitted red eyes with dark skin. And has hind legs instead of legs.

"Get out of here! You fiend!"

"Begone! Evil monster!"

"Disgusting creature! You will die today!"

The Demon King was being bullied and became pitifully lonely, so he anonymously created minions for it and gave it special powers.

The humans call those minions 'The Four Heavenly Kings'.

-[ Timeskip: 10,000 years ]-

The Demon King had children with his minions and started a race and founded a country of its own. Humans called them 'Demons' and 'Demon World' respectively.

The Demon World also consists of many evolved sub-races and hybrids between the humans and demons like Dark Elf, Dwarf, Wild Elf, Vampires, Dragonoid, Beastman etc. Though those are in the minority and are neutral as they take neither the Demon or Human side despite living in the Demon World, so they never really stepped out of their territory unless necessary. Though, there are some exceptions that either joined the 'Demons Army' or the 'Adventurers' Guild' in the Human World.

Tensions quickly raised as conflicts started developing between the Humans and the Demons.

-[ Timeskip: 100 years ]-

The first Great War started.

Both sides advance their arcane technology and science to develop new spells and build strategic magic weapons.

The humans lost horribly.

90% of the human population perished.

The Demon World gained a golden age of prosperity.

-[ Timeskip: 1000 years ]-

The humans rose again to their former power.

The second Great War started.

Again, despite the generous help from the sub-races and hybrids.The humans tragically lost.

95% of the human population perished. And 50% of the population of every sub-races and hybrids were cruelly executed in the Demon World as punishment for helping the humans.

"Ohh My Lord! Forgive us! This child! Please help this child alone!"

*Sob* "M-Mama.. I'm hungry…"

"Ahhhhhh-! Kami!"

The being heartlessly ignored his creations' plea and decided to continue observing.

-[ Timeskip: 10 years ]-

The humans barely kept their race alive. They were driven to the corner of the world.

"Hahahaha! Weaklings! What Lord?! That trash will not even show himself. I'm the new God. Haha!"

"..."

The Demon King of this generation was getting cocky. So the being decided to finally help the humans.

He kidnapped a few random humans from the surface of the earth.

He gave them a mini-system he developed and unceremoniously threw them to his world.

"Ohhh! The Lord summoned Heroes from another world!"

"Quick, call the priestess!"

"At once, your holiness! We will locate them immediately!"

The second Great War started.

The humans finally won.

99% of the demon population perished.

-[ Timeskip: 5000 years ]-

The demons rose again to their former power.

The third Great War started.

Then the fourth… The fifth and the cycle kept repeating.

The world's overall civilization level was slowly advancing with each Great War as both sides tried their best to overtake the other.

"..."

Seeing clear signs of progress. The being nodded satisfied with his work and decided to isolate himself back to his antimatter tower.

-[ Timeskip: 1000 years ]-

"Master, waiting for orders."

The being created the first Automaton.

He called it 'Terminator'.

He then proceeded to create many others, with each generation becoming exceedingly stronger than the previous. The especially distinguished ones were given names and pseudo free will.

Out of curiosity he created a super advanced child Automaton and gave it hyper-growth capability.

He called it 'Angel'.

As predicted, the Automaton child successfully matured like a living being and even developed reproductive capabilities. The experiment was a huge success! That one was his favored Automaton and he secretly kept a close eye at it.

After that, he created many other child Automatons and gave each of them high-level military positions in his Automaton army once they matured enough.

He periodically sends them to patrol around the world.

Just to make sure that his other creations, especially the humans and demons don't self-destruct themselves.

Some very few and highly intelligent 'Magicians' of both the human and demon race barely noticed them and started calling his army 'The Administrators'.

They speculated 'The Administrators' were some sort of 'Agents of God'.

The being was pleasantly impressed by their capabilities and IQ so he rewarded those who witnessed his army with a very small amount of his God Ki. They immediately became fanatical immortals and were called 'Heavenly Gods' or 'Demon Gods' among their peers.

Those Gods and Goddesses steadily amassed followers from his creations and slowly grew in power over time until they had enough God Ki to start building their own mini pocket dimensions connected to this world. Some called them 'Heavens' and others 'Hells'. They even broke the cycle of reincarnation and started guiding their followers' souls in his place without permission.

Strangely enough, not even a single one of those Gods or Goddesses stepped out from his dimension.

None of them dared to go to the surface. They only followed his old method and sneakily summoned some humans from there when things got ugly for their respective followers in the Great Wars.

The being was amused every time when they tried very hard to copy his mini-system to give to those kidnapped humans or when they made some hilarious excuses and especially when they used truck-kun so he let it go.

Because of that, most of the being's other creations quickly started worshiping those Gods and Goddesses instead and completely forgot about him in no time!

"..."

However, the being didn't care. After finishing with the Automaton child project, he was currently sitting on his glorified throne made from a blue hydrogen star. He was deeply thinking about his next project, before he suddenly remembered the surface. And the reason why he was in this world in the first place. An ancient memory surfaced to his mind.

"Touhou Project… Hmm, interesting."

Killua's lifeless eyes slowly closed as he muttered.

"Well, it won't hurt to take a small break for a while… seeing as those mischievous rascals are now doing my job for me."

---

Author: What do you think? Like I promised, this chapter was a brief world building about Killua's world. It shows slight insight to his true IQ, current goal and personality. Also contains hints about hidden variables and events that will appear in future chapters. If you want Points of Views from his world's denizens then I will do it also.