Prologue

Kaminagi Nagare was an expert at Aiki-Jujutsu.
When he was just a babe, barely able to think for himself, he had already defeated his great-grandfather who was the founder[1] of the God-Slaying Aiki-Jujutsu School[2] by throwing him with a single finger. By the time he was in elementary school he had already fought against every genius martial artist throughout the entire world and obtained victory against them all.

He was born for the very purpose of practicing Aikido[3]. Even though his body was now approaching the old age of 85, it showed no signs of frailty or physical decline.
The only things that were affected by the passage of time were the white hairs on his head and the faint wrinkles that sometimes showed on his face.

Of course, his mind remained clear. Just like his body which still kept it’s physical strength, his mind was still brimming with vitality even in his advanced age.
However―― Nagare had progressed this far by using the art of Aiki which takes in everything, molds it, and then releases it to defeat one’s foes. And yet, there was one thing in the back of his mind that still troubled him.

「Empty――」

He was not thinking about it during his daily routine of practicing Kumite[4] by sparing with 10,000 people, but once he had settled down he muttered that word.
Right now he was in the middle of repeating 10 million different Kata[5], but somewhere deep in his heart he could feel a small hole growing wider.

It has been over 80 years since he started practicing Aiki-Jujutsu. From his own point of view, he had yet to reach the pinnacle of strength, but he had begun to have thoughts that his current path might not be able to reach that peak.
Once you decide on your own limits, that is the moment when your path can no longer proceed onward.

However, despite saying that―― Nagare had already become too strong.

He has also saved the Earth from disaster a countless number of times. One time, when he single-handedly invaded a terrorist headquarters to save a very important person, he faced up against tanks and combat helicopters and destroyed him by using his Aikido.

Amongst the times he had saved the Earth from peril, he had once used his Aikido to change the trajectory of an incoming meteorite, had once stopped Mt. Fuji from erupting, and had once sent a mistakenly fired nuclear missile soaring into space by throwing it.

For that reason―― Yes, for that reason, for that very reason, he felt Empty.

But at this point, even if the current Nagare decided to shift his path, the World was now too small for him.

（Oh no, I mustn’t, I mustn’t. For me of all people… to be thinking about such idle thoughts while in the middle of training）

Kaminagi Nagare shook his head, he returned his focus and centered it on himself.

That is why Nagare once again restarted the cycle of repeating 10 million Kata―― This is the path that Nagare chose; the path which dedicated his entire life to the ways of Aiki.

And thus―― In pursuit of improving, Nagare once again concentrated on himself. It was at that time, Nagare noticed something else.

That was the place where Nagare was conducting his training. From that spot, he felt some sort of strange energy leaking from it.

What exactly is this? No, there’s no need to think about it.
Nagare who could sense the flow of everything, since he had already grasped the essence of all things organic and inorganic in the world, he knew that this feeling did not come from this Earth. No, the feeling was similar but somewhat different; a strange and unknown power.

But He could tell what it was. And Nagare’s heart was dancing faster than it had been for decades.
Nagare’s Aikido was perfect. He could grasp the nature of any power the moment he encountered it, and mixing in his own power he could draw out infinite potential.

He focused his consciousness. He felt the waves of energy. Within every power lies a core.
For the God-Slaying School of Aiki-Jujutsu, being able to sense that core is both it’s most basic principle and also the most important technique.

And for Nagare who had been practicing this technique for more than 80 years, finding the core of this unknown power was simple child’s play to him.

「The Supreme Instructor of the God-Slaying School of Aiki-Jujutsu―― Kaminagi Nagare, Iza, Mairu![7]」

In that instant――Together with a spirit filled declaration, Nagare grasped “That” and wove it aside, thus, opening a door through space and time.
Afterwards, all he had to do was submit himself to that flow, like water being guided down a river’s stream. He rode one the waves of space-time, and then……

When he awoke, Nagare[8] had arrived in a different world.