The Seven Princes of the Thousand-Year Labyrinth: Volume 1 (Manga)

Ewan Juno awakens to find himself part of a group of young people who have been assembled in a strange place, surrounded by stone walls and endless corridors.  Gradually, Ewan and the others learn tha tthey are captive in the Castle of the Thousand-Year Labyrinth, and each of them is a candidate to become the next emperor!  This castle, with its twisted secrets and deadly mysteries, could grant their hearts' desires...or bring them to their knees in despair.