Lazarus, the maze of the underworld, is what separates Sigrogana's living, and the underworld, where souls go upon dying. The maze prevents those from going where they should not... usually. Reapers, a race of beings similar to Zerans, guide souls through the labyrinth and away from exiting the labyrinth. They are typically seen as guardians, as well, not allowing just anyone to tread through.
There have been whispers of being capable of entering Lazarus; although it is not completely common knowledge, certain people would have a reason to go.