Sennen Meikyuu no Nana Ouji

A man named Ewan Juno wakes up trapped in a stone-walled, maze-like structure with no memory of how he arrived. He discovers he is one of eight men in the Thousands Years Labyrinth, a mysterious location where they are all competing for a role in determining the next emperor. Only one of them will have the authority to make that choice. As they face the dangers of the labyrinth, including its many traps and changing layout, Ewan must survive long enough to uncover the truth behind the place and find a way out.