The Eminence in Shadow, Vol. 1 (manga)  (English, Paperback, Sakano Anri)

There's only one thing in this world Cid wants to be. And it's not some bland protagonist or the final boss-he has his eyes set on becoming a mastermind working in the shadows. Now that he's been reborn in another world, Cid has been hard at work, building the perfect stage to act out his long-desired role. The issue is that these imaginary adversaries and plot devises exist in this new world...and he's the only one left in the dark!