Sennen Meikyuu no Nana Ouji

A young man, Ewan Juno, awakens to find himself imprisoned in an unknown place, surrounded by stone walls and seemingly endless corridors. Ewan learns that he is one of eight young men, all sent to this strange place—the Thousands Years Labyrinth. Each of them is a candidate to be the next emperor, but only one among them will have the power to choose whom it will be. As each man struggles to survive, Ewan must navigate the shifting landscape of the labyrinth and its multitude of traps, if he is ever to escape and learn the truth behind the labyrinth's dark secrets.

(Source: Seven Seas)