That Time I Emulated the Eminence in the Shadow Lord's Nation

"The world is cloaked in darkness... and I am the blade that severs the threads of fate."
Cid Kagenou is a master of the mundane. By day, he plays the ultimate, blend-in-the-background 'Mob Character' with mathematical perfection. By night, he releases his compressed god-like power to live out his ultimate dream: operating as the mysterious Eminence in Shadow.
But when a dimensional artifact misfires, Cid finds himself thrown into a completely different world-The Great Jura Tempest Federation.
A pristine fantasy world ruled by a cute, friendly, silver-haired slime named Rimuru Tempest.
To Cid, this is the ultimate stage. A global monster superpower? Civilized ninjas roaming the rooftops? Ancient cults hidden in caverns? It's a chuunibyou's paradise! He instantly slips into his dual life-playing a weak, clumsy human servant by day, and a legendary world-shattering night-stalker by night.
There's just one massive, multi-universal problem:
Manas: Ciel exists.
Within five minutes of his arrival, Rimuru's absolute, god-tier AI partner fully analyzes Cid. She cracks his energy signature, deciphers his dramatic poses, and reaches a terrifying conclusion:
This boy has the power to accidentally collapse reality... and he is doing it entirely because he thinks it looks cool.
To save his nation from being vaporized by an awkward teenager's mid-life existential crisis, Rimuru Tempest receives a direct mandate from Ciel: DO NOT BREAK HIS DELUSION.
Now, the Supreme Ruler of Monsters is forced to act as the secret director for an overpowered teenager's private theater production. Rimuru has to fake villain plots, Diablo is losing his mind trying to crack 4D chess moves that don't exist, and to make matters worse-the Seven Shadows of Shadow Garden have just crossed the dimensional rift!
Let the ultimate, multiversal game of misunderstandings begin!