Before going anywhere, Zack decided to check things in the north and experiment with ways to close the portals without exposing himself too much. The monsters that he found there were nothing really hard to deal with, so he had a lot of time to think about and plan the future.
Since Zack didn't know how the situation would look beyond their continent, so he had to prepare for all kinds of possible outcomes and react to them as fast as possible.
The possibilities were many, even though he had already found some situations nearby of people joining the overlords. Lands filled with nothing but monsters that were breeding endlessly or places were humans became like slaves for the overlords. There is also the possibility that he will find nothing in those places, even a single sign of life.
