How to build a labyrinth Empire

This world is about to end.

One day, Nino, a humble alchemist, regains memories of his past life and realizes that his world is eerily similar to a certain game. He also realizes that he is on a notoriously difficult route to the destruction of humanity.

However, no one would believe him if he tried to explain. Despite his best efforts, he fails miserably and is nearly captured as a criminal.

Nino narrowly escapes the capital city and arrives at the village that was the starting point in the game. Nino's goal was a dungeon hidden very close to the village.

If the surface is going to be engulfed in flames, then he can live underground...