Fifteen Days of Mystery

The task of the entrant is to "save" what to redeem? To be fair and noble, they are trying to save the world. To put it too much, they are redeeming themselves. The world's resources are exhausted, chaos, collapse, and extremely cold weather. People who felt the wrath of the universe begged for mercy, but what was the use? One month after the disaster began, the world was controlled, and only one voice echoed around the world, "Welcome to the Fifteen Days ~ The Lost Realm!!!"