The Eminence in Shadow, Vol. 2 (manga)

When the foul-tempered Princess Alexia is captured by the Cult of Diablos, the Shadow Garden takes the stage, assaulting the cult’s hidden base. Crossing swords with the kidnapper, Cid gets the chance to make his true debut as an eminence in shadow (and show off his totally awesome secret technique). As the attack lights up the night sky over the capital, all will know of the hidden powers that lurk in the darkness!