Rimuru's changes

It's been 10 million years since Rimuru defeated Yuuki... He would get quite bored in all these years, so Rimuru decided to turn back the time of the entire multiverse (and the others) to start again in the cave, but he could keep all his previous abilities and strength through Ciel.

Note: Rimuru will not have such a friendly character but I will make him a bit evil/badass ^^ The story also goes after the light novel therefore it might spoil the light novel for them.