The Eminence in Shadow

One big fat lie and a few twisted truths. 

Even in his past life, Cid's dream wasn't to become a protagonist or a final boss. He'd rather lie low as a minor character until it's prime time to reveal he's a mastermind...or at least, do the next best thing-pretend to be one! And now that he's been reborn into another world, he's ready to set the perfect conditions to live out his dreams to the fullest. Armed with his overactive imagination, Cid jokingly recruits members to his organization and makes up a whole backstory about an evil cult that they need to take down. Well, as luck would have it, these imaginary adversaries turn out to be the real deal-and everyone knows the truth but him! 

(Source: Yen Press)

Cid is a boy who reincarnated in another world, and decided to enjoy a scenario of being "the eminence in shadow, someone who meddles with the story from the shadows, and exhibits his true power in secrecy". Thus unfolds the story of him and the secret organization he leads—shadow garden—as well their their pleasant friends! An easy-going 4-koma manga starts right here and now!

A young boy named Cid Kagenou enjoys being a "shadowy power" in another world, and with the help of the girls he has made his subordinates - the Seven Shadows - he takes them on the side of justice (in all seriousness), and then the darkness in the world (maybe) will disappear. This is the start of a serious comedy about the Seven Shadows (and the main character) being the strongest, an overwhelming chuunibyou syndrome, and misunderstandings!? 

(Source: ComicWalker)