The Eminence in Shadow, Vol. 1 (manga)

Cid Kagenou has a unique ambition: to become a hidden mastermind operating from the shadows. After being reborn in a fantasy world, he sets out to create the perfect environment for his clandestine activities. However, Cid discovers that the imaginary enemies and plots he devised are real and unfolding around him. As he navigates this new realm, he must adapt to challenges he never anticipated, all while striving to maintain his secret identity as a powerful figure in the shadows.