Goddess of Victory: Nikke - No caller ID

No Caller ID follows the story of Counters squad who are tasked in finding the source of a mysterious transmission sourced from the surface, believed to be human survivors.

One day, the Ark received a message with no Caller ID. The source of the signal came from the ground. However, in the official information of the Central Government, there were 0 survivors on the ground. What exactly is happening?