One day, a mechanical but distinctly feminine voice was heard by all humans. This is the voice who later introduces herself as the “Operator”.

  [A hunt will soon begin. Prepare for combat.]

  And the moment they heard the sentence, every man, woman, and child were teleported to a blank white room alone. The room itself was not large; just slightly over 66 m^3. And in the middle, a large hologram appeared.