After many, many months of futile attempts and diligent preparations, the group of heroes at last succeed in re-infiltrating the Demon Lord's domain. Two goals ignite the fire of determination in their hearts: the rescue of a dear friend, their leader, who sacrificed himself to save them, and the long-awaited elimination of the Overlord of Darkness. But as they navigate the lavish yet eerie corridors, the heroes are unaware of how terribly late they are.