Rimuru Met AlternativeSelf

prologue

Let me explain about the cardinal world created by the Will of an unknown entity out of boredom. He created numerous worlds and parallel dimensions and sent parallel existences to each cardinal world, each with some memory or knowledge creation. There are only a total of 7 cardinal world copies, unlike the other worlds he created. Each cardinal world has a different type of heaven and underworld. In one parallel world, he created 7 primordial angels and demons, but one of the 7 worlds doesn't have them.

Now, about the True Dragons: in 2 worlds, there are 5 True Dragons - Velzard, Velgrynd, Veldanava, Master Rimuru, and the fifth has another Cardinal World Master. Rimuru isn't a True Dragon in any of these worlds. In the other 4 worlds, the Master is Veldanava's daughter, who becomes Girl Rimuru, Velgrynd's daughter, and Rudra, the True Hero Rimuru.

Now, my master has decided to visit the other worlds that the unknown entity created for fun. Of course, I will manage the Voice of the World. The master is slightly bored because of paperwork and other obligations like political visits to nations. The unknown entity contacted him through some unknown means and informed him about all the worlds he created. The only world he didn't create is this one; the other worlds are just imitations.

Now, the problem my master is facing: Even thought acceleration wasn't useful in front of the mountain of paperwork (meaning all he needed to do was create a pseudo mana to handle that), it's only been 10 years since the defeat of Feldway and Ivaraj. The other 3 True Dragons accept him as a brother. Velzard treats him like a baby brother, but I don't mind. Velgrynd sees him as a matured brother. Veldora, you already know him, right? He still treats him as a crazy friend...

Ugh, fine. So, imagine Rimuru's imaginary space like a freakin' cosmic filing cabinet. Each drawer in this cabinet represents a parallel universe, and inside each drawer, you've got folders for different timelines. But it doesn't stop there, oh no. Inside some of those folders, there are more folders, containing even more timelines. It's like a never-ending nesting doll of universes and timelines, all neatly organized... in a cosmic, arrogant kind of way.

Let's break it down further. Say you're looking at one universe. Inside that universe, there are multiple timelines—like different versions of the same story. But wait, there's more! Each of those timelines has its own set of alternate universes, each with their own timelines, and it just keeps going, like some twisted cosmic Russian nesting doll.

And Rimuru's imaginary space? It's like the master storage room for all these timelines and universes. It can hold everything from entire civilizations to individual beings, all sorted and organized in this mind-bending labyrinth of existence. So yeah, basically, Rimuru's imaginary space is like the ultimate cosmic storage unit on steroids.