From his own perspective, Yamato Bouichirou had already lived for hundreds of years. He would appear and disappear within many different eras, but he experienced disappointment in every one of them.

Those disappointments had made him stronger, but they had also made him stubborn. This was caused by his own inability to resolve the contradiction that existed at the base of his heart. No matter how many years or centuries he spent, he could not resolve that contradiction.

Once, far in the future from the era Akuto and the others live in, Bouichirou had worked in a university research laboratory and had been taught information integration science there. This was before he became a time traveler, so it was the very first era of his life.

“If a certain race has inferior intelligence, it is proper that the superior race guides them.”

Those words had been spoken by Sudou Rimu, Bouichirou’s guidance teacher.

“You can’t mean that!”

Bouichirou’s disgust reflexively came to the surface. Racial discrimination was a detestable practice of the past. The system of slavery which had caused so much suffering for so long had certainly been based in the reasoning that those races which had achieved civilization were superior to those which had not. It was a disgusting way of thinking.

But Rimu shook her head with an expression saying that she had predicted his reaction. A hint of disappointment was visible in her eyes. Bouichirou’s shoulder’s drooped when he saw that expression.

“What kind of cruelty is this?”

While in the research laboratory, Rimu would act as his guidance teacher rather than his lover. And to ensure Bouichirou kept that in mind, she would occasionally ask him cruel questions.

“No. It is not all that cruel.”

As she spoke, Rimu let out an obvious sigh. She was a genius in the field of information integration science and her appearance was without fault. But she held such faith in reason that she did not even attempt to hide her scorn for those who took actions based on emotion. That was her one obvious flaw.

“So even you give that response. But think about it. Those words are absolutely correct in and of themselves,” said Rimu in admonition.

“I see,” said Bouichirou with a nod. “From a scholarly perspective, I suppose so.”

“But when you try to apply it to reality, you suddenly cannot accept it. If an intelligence greater than mankind did exist, who would accept that?”

“Why are you bringing this up?” replied Bouichirou because he could not grasp her intention.

Rimu replied with a much more serious expression than he had expected.

“Because mankind will be destroyed.”

“Sigh. I regret the fact that I know you too well to think you would be joking,” said Bouichirou while doing the best he could to not grow too serious.

However, Rimu’s serious expression remained. This terrified Bouichirou even more.

“Destroyed? Are you speaking figuratively? Or…”

“I mean it literally,” declared Rimu.

Bouichirou looked around the laboratory. No one was around to hear them speak. Rimu had clearly chosen this moment.

“Is this a topic you cannot allow to get out?” asked Bouichirou with a gulp.

Rimu nodded as if to say, “So you’re finally catching on.”

“Yes, of course. Only you would think I was sane if I said this. If we do not reach the final battle, mankind will be annihilated by a certain individual.”

“That is complete nonsense,” replied Bouichirou reflexively, but he then spoke back to Rimu to calm himself down. “You are the one that created the foundational principles for the weapon to defeat the demon king. Thanks to that, we can immediately eliminate any demon king that appears from now on. So why will mankind be annihilated if we do not reach the final battle?”

“The theology supporting my research was fundamentally flawed. That is why a new demon king is born no matter how many times the demon king is defeated.”

“Flawed?”

“Yes. The G.o.ds already have a will of their own. We have misread the situation. And have done so for hundreds of years.”

“So are you saying the G.o.ds will destroy mankind…? No, you said it would be a certain individual…”

“Yes. It will not be the mechanized G.o.ds that are no more than a system created by mankind. There may be a real G.o.d. The G.o.ds of antiquity. The being called G.o.d when mankind first created religion. You could call it the G.o.d of the Old Planet.”

Rimu’s words sent Bouichirou into an indescribable state of confusion. She was saying a real G.o.d might exist. And she was saying it would destroy mankind.

Bouichirou was left completely speechless, so Rimu gave a resigned smile.

“Is that really your reaction? But… That is my thought.”

Bouichirou was not someone who would not understand the situation after hearing that much. He was filled with fear when he thought about what would happen if that was true.

“So that is why you asked that first question!”

“Yes. Logically correct statements can lead to emotional backlash. ‘War can be justified.’ ‘White people are cowards.’ Mankind has definitely been given an abundant lifestyle to stop saying that sort of thing. But what if that is not what mankind was born to do?”

“Are you saying humans were born to discriminate and slaughter each other?”

“Perhaps. The G.o.d that created mankind is trying to destroy mankind and the mechanized G.o.ds we have created are trying to save mankind from that.”

Rimu’s worldview caused Bouichirou to hold his head in his hands. He could not decide whether she was right or not.

“D-do you have any proof?” he asked.

It would be a lot better if Rimu were simply insane. But Rimu calmly shook her head.

“As is often the case in information integration science, I can only speak philosophically. However, the reason certain types of animals do not hesitate to kill other animals is because they are as identical to their surroundings as a drop of water in a pool of water. The only creatures that resist becoming one with nature in that way are those with great intelligence such as us. You could say I believe intelligence is the same as being in opposition to becoming one with nature like that. However, the G.o.ds we created are the same as nature while still possessing great intelligence.”

“Then this idea of mankind being destroyed…?”

“Yes. I heard about it directly from the G.o.ds. I spoke with a shrine maiden of Suhara. No one had asked the right questions, so the answer had never been arrived at before. That is how it was hidden for hundreds of years. The reason a demon king is born and the reason we are driven to war have both been kept hidden for so long.”

“I cannot bring myself to believe this. It is possible you are being deceived. Why would mankind’s numbers need to be lowered in order to save it? It makes no sense.”

Rimu’s shoulders drooped in resignation when she heard Bouichirou’s opinion.

“This is where you have no taste at all. But there is no time, so think about it on your own. However, I do have proof that the G.o.d of the Old Planet exists. We constantly use mana to transfer ourselves through s.p.a.ce, but why can we not pa.s.s through time? We cannot break the barrier of time with technology that uses mana. In other words, we cannot interfere with the dimension itself. And yet we can transfer through s.p.a.ce. That is a contradiction. The reason for this is the Law of Ident.i.ty. We cannot help but think that we are ourselves. That is the source of our intelligence as living beings. And that was created by the G.o.d of the Old Planet,” said Rimu. She shook her head in disappointment when she saw Bouichirou clearly still did not understand. “You do not need to believe me. I will leave you a chance to research. Once you complete that, you may come to understand what I mean.” Rimu displayed a mana gauge and showed it to Bouichirou. “This is the inherent vibration of my mana. If you use this, you can overcome the barrier of time.”

“What? That’s-…”

Bouichirou swallowed the word “ridiculous”, but he still began wondering if Rimu truly was insane. Just as Rimu herself had said, the ability to travel through time had been researched for a long time but had produced nothing but failures.

“You will see once you try it. It will work because I am the Law of Ident.i.ty.”

Rimu smiled gently as she spoke.

Bouichirou could not come up with anything to say in response. He simply said, “I will research it.”

“You must not publicly announce anything you heard here. The ability to travel through time must remain a secret until it is complete. I will come to see your results periodically.” Rimu began to leave the lab but turned around at the last second. “What do you think would happen to me if I publicly announced this?”

She was still smiling, but she looked somehow sad.

Bouichirou understood the meaning of that expression. Rimu would be deemed insane. No one would believe what she said and she would certainly be imprisoned if she took action to carry out this dream of hers.

Bouichirou felt Rimu’s smile came from despair. And he could only think that despair came from his reaction. Rimu desired a comrade who thought the same as she did. And he had been unable to think that way until receiving her explanation. Most likely, he was no different from the majority of people.

“W-wait…”

Bouichirou tried to stop her, but Rimu left without replying.

Bouichirou never saw Rimu again. She had said she would periodically come by to see his results, but she had taken action to support the demon king shortly after leaving.

Bouichirou had been unable to heal her despair. He had immersed himself in his research as if to ensure he still had that small connection to her. He ultimately developed technology to control time and s.p.a.ce, but he realized he would never have a chance to save Rimu when he learned he could not return to a time he had already existed in once. On top of that, the instant he had used the technology he developed had been the exact instant of mankind’s destruction.

Whenever Bouichirou closed his eyes, he saw that unforgettable scene in the back of his mind.

A mysterious eddy rose up in the dark red sky. A giant and ominous existence that defied description existed within that eddy. The tens of thousands of troops in the demon king’s army drew a spiral around that eddy. The transformed demon king stood at the front of that army. And next to him was Rimu.

This apocalyptic and majestic scene seemed to split Bouichirou’s body between the puny mental images of having betrayed his lover’s trust and being betrayed by his lover. If possible, he had wanted to take his own life. However, Bouichirou had understood that he would become the last of mankind. During his research, he had become certain that the G.o.d of the Old Planet intended to destroy mankind.

Bouichirou needed to flee. He became mankind’s lone time traveler and was the only one who could change the situation.

And afterwards, Bouichirou remained mankind’s lone time traveler and he experienced despair for a long, long time.