"The Ancient Era took place several thousand years ago. Back then, the world was much less developed than it is now. Up until then, the concept of a class 4 was foreign to people, and at most, class 3's roamed around. But that all changed one day when the angels descended on this world.

The angels are beings of incomprehensible power, and when they came, they brought with them the teachings of the Church. They established an entire kingdom that we once knew as the Holy See and gave us our Bible. After that, they left. Nothing much was originally planned to come of their arrival. However, they left behind them an unexpected benefit. Since they were supremely powerful beings, they unintentionally raised the mana density of our world.

From then on, the entire world skyrocketed in power. Class 4's came into existence for the first time, and with their appearance came the establishment of the world's greatest Empires. The Spire, the Sword School, the Enchanted Mountain, the United Empire, the Elven Tree, the Dwarven Empires. All of these Empires appeared during this time, and until now, nothing was capable of toppling their rule.

There were also several other Empires just as powerful as them that appeared as well. However, those were lost during the Great War.

The Great War was a conflict between Animal and Human. Back then, animals had lived in abundance on the human continent, and vice versa. However, an unexpected object was one day found, and it caused a war between humans and animals.

The object, was a heart. An incredibly powerful heart. One that could output immense levels of energy in seemingly unlimited quantities. When it was discovered, greed got the best of both sides, and after the United Empire allied with the elves and dwarves, the humans were driven to their one continent. The animals were also driven to theirs, but with them went the heart.

Of course, the human Empires wouldn't give up easily, and after a few years of intermission between the sides, they took the fight to the United Empire. There, an unprecedented battle took place. In the end, out of the entire population of class 4's, almost 90% were killed, with the humans having lost the battle in the end.

Thus, the heart remained in the United Empire, and the two races went into isolation on their continents. Thousands of years later, the Ancient Era ended, and the class 4's that lived through the Great War are now known as the Ancients."

The Pope stopped there, and Dream, Luna, and Iris sat there for a bit, processing the information.

"So... Angels descend, the world prospers, the heart appears, and then a war breaks out."

"Correct. And, although it's only a bit of speculation, many used to say that the heart appeared when the angels did. They say that a foe of Heaven attempted to escape to this world, only to be tracked down and ultimately killed. Many think this is the only reason why the angels appeared at all."

"Huh... Now that's all very interesting, but how do the demons fit into this?"

Dream reasked his original question, having not gotten a clear answer.

"The demons were spoken about in the texts that the angels gave the Church. They said that they would come one day, although they didn't say when. But when they came, it was said that they would seek to take over the world. If that happened, this world would be doomed and they would attempt to connect the world to their territories, bringing about the descent of a Demon Lord who would turn this place into a breeding ground."

"Connect it to their territories?"

"It's not clear, but I've always assumed that Heaven and Hell have territories. As to what extent their territories cover, I'm not sure. The books don't go into great detail."

"Right... What about this Demon Lord? How powerful is one of those?"

"I'm not sure about that either. However, it's implied that they're at least on the level of an angel."

"And how powerful is an angel?"

"More powerful than a Saint who is supposedly a step above a class 4. However, nobody had ever risen to the level of a Saint, so estimating the power of any of these entities is impossible. The only thing I can say for sure is that we would be truly and utterly doomed should a Demon Lord descend."

"...Yea. We would."

Dream's brow furrowed as he thought about it all. The demons have taken over the world, and Iris was sensing changes in their kingdoms. According to the Church, this was because they wanted to somehow connect to Hell's territories.

"...But how would they go about connecting to their territories?"

This was the question Dream was now most concerned about. Although the world was taken over, given enough time he had the confidence to take it back. It might take a year, or maybe less, but he could do it. However, if they were going to be put on a timer, that would change, and he would have to act faster than initially planned.

"I'm not sure how they would go about doing this, but whatever they do, it's going to be where they're most powerful. Allowing for the descent of a powerful being like a demon lord won't be easy. They had to take over the world for their plan to even be possible. That's a clear indicator of the stringent requirements."

The Pope spoke as he made his assumptions. Dream nodded in agreement. It was sound logic.

"So we need to go wherever they're most powerful and stop whatever they're doing. At the very least, we need to delay them... Alright, I think I know what to do."

Saying that, Dream stood up from his seat.

"Thanks for the information, Pope."

"Of course. If you need help with anything, just let me know. Our fight may not truly be over yet."

"Mm. Then I'll be going."

Saying bye, Dream left with the girls, heading back up to the factory.

This story originates from Royal Road. Ensure the author gets the support they deserve by reading it there.

............

"So what do you plan on doing?"

Luna asked him as they walked through the factory. Dream had been pondering for a while.

"...I'm conflicted."

"About what? Can't you just nuke them?"

Iris spoke as if the solution were simple. He shook his head though.

"While I could do that, it would pose a problem for me down the line."

"What problem?"

"Right now, the changes you're seeing are only in the strongest kingdom on the demon continent, yes?"

"Yea. The other ones were normal."

"So that means whatever the demons are doing, we at least know it's there. But if we were to nuke them, it would force them to change locations."

"So?"

"One of the locations could be in the ocean, and if they were to move there, we would be greatly hindered in our efforts to stop them. Not only would it be difficult to find them, but even if we did, nuking them wouldn't be an option. I'd either have to come up with new weapons, or we'd have to fight them ourselves, and we both know that's not quite doable."

"...So you aren't gonna wipe them out?"

"I don't think I will. At least, not yet. What we can do is wait until they make progress. During that time I can develop some more, and when the time comes that we need to stop them, I'll have the power to continue stopping them even if they were to move to the ocean again. We'll bid our time and strike when we need to, drawing out the process as much as possible to accumulate power."

"Huh. Sound good, I guess. But shouldn't we at least see what they're doing?"

"Of course. That's one of the easy parts though."

"Mm... Oh! By the way, are you going to do anything about your class?"

Iris suddenly remembered something and asked.

"My class?"

"Yea! Your class advancement, dummy!"

Iris shouted with a bit of exasperation as if it were obvious. She didn't forget the absolutely absurd fact that Dream was still a class 3.

Luna also nodded when she remembered that fact too.

"She's right. You didn't even do your class advancement when the demons were taking over. Now that things might be even worse than before, maybe you should think about doing it."

"Hmm, I guess you're right."

Dream nodded when he thought about it. Before, the main reason he hadn't done the advancement was that he was weak. When the demons suddenly appeared from the oceans, he had only regained A+ stats. However, in the two months since the final battle where the Haven was sealed, he had advanced once more.

He was now back in the S tier!

Although his stats were only S-, it was still a great accomplishment. It had taken him a long time, but it had been done. Not only that, but the gray mist that was spreading through his soul was almost completely assimilated.

So far, the gray mist had spread through a little over 90% of his soul. Odd thing was, its speed gradually picked up over time as it spread more and more. It might've been because of how much more gray mist he could create from the conflict between the girls' contract. He had gotten more powerful, and with more power he was able to exploit the conflict more. Now, it was currently penetrating through a small remainder of his nucleus.

Even if he were to just wait around, it wouldn't take much longer for the mist to finish its assimilation. But now that they were on a clock, he thought it might be good to try and speed up the process.

"I want the mist to finish spreading and maybe get back up to S stats before advancing."

"How long will that take though?"

"Maybe... two, maybe three months at most."

"That's quite a while. I guess our urgency depends on how fast the demons progress, but the more time you have at your strongest possible state, the better."

"Indeed. That's why I want to try and speed things up. I'm thinking we should be able to mess around with the conflict of your contracts and speed up the gray mist production process. Or maybe come up with another production process."

"Mess around? That's how you describe playing with your own life?"

Luna frowned at his suggestion. Anything that pertained to their contracts and the conflict between them was extraordinarily delicate and she would avoid 'messing around' with it as much as possible. Dream thought otherwise though.

"Things aren't the same as back then. Not only has the gray mist strengthened me, but it's now present throughout my soul. Even if your powers went and tried to spread through it, the mist would be able to neutralize it, unlike last time where it was just destroyed."

"...I don't know."

"Just trust me. I'll stop if I need to. Besides, the conflict of your powers can't be stopped anyway. Taking advantage of it as best I can is the most profitable route."

"...Fine. Not like I can stop you anyway. Just be careful."

"Sure, sure. I'll get started now then. No time to waste."

Saying that, Dream plopped down on a couch where he commonly did his experiments. The girls also sat with him, staying there just in case.

Soon, Dream had a view of his soul. He could see the Nexus skill, the two contracts of Luna and Iris that pulsed with white and black power, and the capillaries that acted as the barrier between them.

On each capillary were attached three strings. One connected to his nucleus, one to his Particle Manipulation skill, and one to his Arcana skill. These strings constantly injected his clear mana and mediated the forces without rest. Luckily it didn't take much energy to do this, otherwise Dream never would've been able to last so long.

As of now, within the capillaries were thousands of tiny needles. These needles passed between the black and white powers, gathering some and clashing against each other in the middle. This clash made the two powers annihilate each other, and this annihilation is what produced the gray mist, and there was a thick accumulation of the mist in the center of the capillaries. From there, the mist traveled up the strings and out toward Dream's skills, filling his soul and turning it gray just like the mist. However, it wasn't moving as fast as he wanted, so he started thinking of a way to increase the production and density of the gray mist.

'I can't directly control the mist. I can only produce it. I don't know if simply producing more will make it denser, but it'll definitely speed up the spread. And once it's totally spread, maybe it'll start solidifying then. So, how do I speed up production...'

Dream pondered over the issue. His needles that managed the clash of the forces were already very efficient. They had been optimized over time since this wasn't the first time Dream had thought about increasing production. Plus, Sophia just wanted to make sure it was more under control. But that meant that they were already as good as he could make it. There wasn't much more he could do to increase efficiency.

At least, not if he kept things the way they were. If he wanted something better than the best, he had to change up the paradigm. That would mean revamping the entire system. It would be more dangerous, but he was confident in keeping things under control.

Now he just needed to figure out how to change the paradigm. Luckily he had a few ideas.

'The first way I can do this is through simple addition. If I want more mist, I need more points of conflict. I'll need to increase the spread of the contracts so their power can be utilized more. To do that, I'll need more strings and more capillaries. But I'll need to keep energy consumption within certain limits. I can't consume more energy than I can regenerate, otherwise the system will break down over time.

However... The second way is by changing the battleground itself. Two energies from two different sources that wish to combine with each other, but instead destroy each other. I can think of it as a reactor, and the byproduct of the annihilation is the gray mist. Right now I'm not really combining the energies as a reactor would, but simply by colliding them like armies. I can change that though. Instead of colliding them head on, I can manipulate them and mix them in one big pot. I just need to find a containment technique that can keep the energies from dispersing during the annihilation, just like a reactor...'

After thinking about it for a bit, this was the idea he came to. Instead of breaking everything apart into pieces, he wanted to bring it all together. He wanted to apply the principles of his fusion reactors to the combination of opposite energies. While it was a bit different, the main points were still annihilation, production, and extraction.

So with that framework in mind, he went to work alongside Sophia. The first thing they did was design the container for all this. It had to be strong enough to handle the pressure from opposite energies destroying each other as well as have the power to force them together. Something like this obviously wouldn't be easy to make, but as they started hypothesizing, the shape gradually began to take form.