@kwendy
This is a spoiler. It will be revealed waaaaayyyyy later. You will probably read it after two-three years, so Ai-chan doesn't feel guilty spoiling this.
All the Shadow Garden, starting from Cid himself, makes use of subordinated slimes. Humans have a limit to their mana capacity, slimes don't. All the executives of Shadow Garden has slime on their bodies and in their blood and they can control the slimes without any side effect. Normally you wouldn't fuse with monsters because it will turn you into monsters too, but Cid has a technique that makes it possible to have symbiotic relationship with slimes. Their clothes and swords are actually made of slime.
If I'm not mistaken, the noobs of Shadow Garden only wear slime suit but are not fused to slimes like Cid and the executives. Haven't read the story for almost a year, so details may be inaccurate, though.
@kwendy It will be explained at some point. We've got time. The WN's translation has 203 chapters and it's not over. The manga's translation only covers the first 40 chapters.
@kwendy
There's a few reasons forthem being stronger than everyone else, but these things will be explained in due time. I can list some, just know some of them are legit spoilers
First, and least spoilery:
due to magic boosting no one has actually bothered to learn much good swordfighting. Cid learned just about every martial art in his previous life, taught his disciples, and they've passed that on to all of their followers.
Secondly:
all the girls in shadow garden had the demonification disease, which is actually just them belonging to the bloodline of the evil demon Cid thinks he made up. They normally die from the disease which is actually just the powers manifesting themselves, but Cid curing them leaves the power without the drawbacks
As for Cid himself being OP, he's been consciously training his magic since he was born. Constant training plus children learning faster = OVAR 9000 MAGIC POWER!!1!
That last one's not even a spoiler, that was already explicitly shown.
@Onithyr
The worst part of it being true, is that he still believes it's fake. And even so, acts on pure cruelty.
If he knew what he was doing and chose the theatrics just for mood it would be one thing, but he happily kills anyone, even when he believe they are just innocentlly trying to be chunni like him or go along with him. He kills even believing the other party is innocent, just to satisfy his chunni. That's complete madness.
He's constantly just a few misunderstandings away of killing a bunch of real innocent people.
@Akxera That's the fucking point. This whole manga is about how chuuni he is and how the world molds to fit his childhood fantasies. To me, first and foremost, this is a comedy. And it does that pretty well lol