Monsters and Phantoms, the opposition between these two groups was well known to every common human as well as the fact that unlike monsters, each Phantom had an assistant - an Operator.
People became Operators for a variety of reasons, but most often it was heavily influenced by the family of the future student.
This was one of the reasons why most students at Operator Academy were unable to pass the final exam and become an Operator because as in any field, it took desire to succeed.
Wealthy parents realized that the chances of their child becoming a Phantom were slim, especially if none of them or their parents were Phantoms.
This was such families' way of associating themselves with the Dead Lands. Sure, there was an easier and more accessible way for almost anyone to become a military personnel, but it was not as prestigious as the role of Operator and much more dangerous.
