Starts 20 years after Tensura WN ending

Ciel had integrated herself into Rimuru to be capable of altering reality to execute her master's will. This power came at the cost of Rimuru's closest friend. However, transforming her eternal partner into a supreme being knowing that she would lose all sense of self, this was ultimately Ciel's decision.

As soon as he realized she had disappeared, he flew into a rage. Rimuru's grief was boundless, and threatened to swallow the universe. To prevent the destruction of all those dear to him, he retired from his position of chancellor, bid his friends and subordinates a teary goodbye, and vanished, cutting them all off from his soul corridor.

He understood she made this choice for him, and he would only hurt those he cared about by staying. Recalling the miserable looks on his friend's faces, he shook his head. He had already decided to not travel back in time, or otherwise attempt to re-create Ciel. He felt that she had made her choices, and while he couldn't agree with them, he could accept them.

On this day Rimuru vowed to never get too attached to anything or anyone ever again. His new purpose in life would be to wander the infinite dimensions he created without a second thought.

- Fast-forward a few dozen centuries -

Without Ciel to rely on, he had already forgotten his life back in Tempest. Even with his vast memory, Rimuru still couldn't remember his youth, he couldn't even remember what created him.

The truth is, Rimuru himself doesn't know how old he is, though age can't really be said to apply to Rimuru in the first place. The only thing he has left is his name.

Throughout his travels the ancient god caused chaos as he slaughtered anyone who upset him. Due to his overwhelming aura, the gods of whatever dimension he visited flocked to challenge him like moths to a lamp. Rimuru looked on at their efforts with pity. Whether it was an evil god looking to dominate him, or a kind god who wished to protect their realm, they all died the same when faced with an absolute. A simple thought could erase any enemy instantaneously.

Of course, he never would need to use this power. His preferred method of fighting is simply to walk over to them and shatter their root with a single punch. You have to keep in mind, 'walking' to Rimuru is the equivalent of instant teleportation to anybody else.

At first, Rimuru worried his combat skill would become rusty if he just depended on his overwhelming power. This thought quickly drifted off to nothingness as he realized time and time again that nothing could stand up to him, and he stopped worrying about it.

Eventually, his sightseeing grew old and monotonous, and he decided it was time to settle down. As he tore through space-time again looking for a place that gave him any interest, a flicker caught his eye. He approached the two individuals sparring, whose fight emitted enough energy to interest him. The demon and the dragonoid looked at him in confusion.

"Who are you and why have you come h- RIMURU!?" Guy Crimson yelled, bewildered.

Rimuru did a double-take, his eyes wide. For the first time he could recall, he understood the base language that he was being spoken to in. Of course, he could create that intelligence instantaneously, but judged it not to be worth the trouble. Why would a star deign to notice a stray atom passing by?

He wondered if this was due to him approaching the entities rather than them seeking out him.

Milim and Guy had been sparring in space to pass the time. After a complex series of [Dragon Nova] which had all been dodged by Guy, Milim was about ready to admit defeat. Her bloodlust had weakened over the years, and she was much more pleasant to be around in general. However, an ethereal presence approached them.

Milim at first was terrified; her [Milim Eye] was giving her the response of "Impossible to appraise", which had never happened before. She tugged on Guy's shoulder, and was about to ask him to run away, when his words reached her. She looked back at the presence, and saw someone who even the most optimistic believed would never return.

After Rimuru's disappearance, the status quo was maintained until Hakurou died of old age. Most Tempestians thought he was still watching over them, but Rimuru did not return for his funeral. This broke the hearts of many, but they soldiered on. Besides Hakurou, and a few years later, Shuna, the rest of Tempest's inner circle were doing just fine. The monsters kept on innovating, albeit without Rimuru's ideas, growth had completely stagnated.

Out of Shizue's former students, only Chloe Aubert was alive. Kenya had been unfortunately unable to hatch his hero egg, and Hinata had fallen from the realm of sage after being brought back by Ruminas. On a further note, Masayuki had been able to reach the sage realm, and was still with Velgrynd to this day.

Ramiris and Veldora undoubtedly would have wished to continue exploring other worlds, however, they were unable to use the dimension gate anymore. It seemed that, for unknown reasons, Rimuru had sealed off this world.

Benimaru was unanimously declared the successor to the throne of Tempest, and maintained a fair and just rule, although there wasn't really any work that had to be done. He was also the only high-ranking existence to have children, in fact, he sired two handsome boys. Tragically, they had not inherited his immortality, and so they passed on along with his two beloved wives in what seemed like a blink of an eye

It had been over 3000 years since their beloved Rimuru left them.

Rimuru POV:

I suppose that I should ask them how they know my name, after all, they might know things about me that I don't know. Even I am unable to explain my existence; if there is even a chance they possess information for me, I must know.

The pink-haired dragonoid still had not opened her mouth, so I walked up to the demon and after grabbing his head, I softly spoke in his ear in the language he used.

"How do you know my name?"

Guy Crimson instantly regretted opening his mouth. Rimuru's aura was incomparable to before he left, the fact that it wasn't restrained at all showed that there was a fundamental difference in this person. And now he felt an abyssal touch grasping his very essence. One wrong move here would spell his final demise, there was no coming back from this.

Teeth chattering, he blustered "Why are you attacking me? We were allies, what happened to you?"

Rimuru let go, deep in thought. It was at this moment that Guy realized Rimuru didn't remember anything. Guy considered trying to lie about their relationship, but if he had called Rimuru a friend, he felt that Milim would contradict him to earn favor.

Speaking of Milim, she now clearly understood the situation. She was about to punch Rimuru to make him let go of Guy, but Guy frantically shook his head, and Milim stopped herself.

He heard Rimuru speak again.

"So does that mean you know who or what I am?"

Guy, sensing his chance to be seen as helpful, retrieved a book from his spatial storage. It was a copy of the one of a kind book written by Rimuru himself about his life. He handed it to Rimuru, and stated that the story inside would explain everything

Rimuru touched the book, and absorbed all the information inside. It gave him a general understanding of the person they thought him to be. Still, he did not feel any of the books contents resonate with his demonic soul. None of the things it claims he did are something he would have any reason to do.

Raising his hand, Rimuru mentally checked out with a whispered farewell to the demon. Right as he was about to strike, a voice spoke to him.

How have you been, Rimuru?