The Eminence in Shadow, Vol. 5 (manga)

In the depths of the Sanctuary, where ancient memories of mighty warriors slumber, Shadow Garden lays bare the long-hidden truth behind the demon Diablos and the hero Olivier-all very critical plot information that Cid pays zero attention to because it's time for the semiannual Bushin Festival! Playing the part of a weak-looking guy who's actually super-strong is Cid's raison d'être, and where better to strut his stuff than a tournament arc