In the year 2015, on a night when the moon turned red, monsters appeared.
The monsters indiscriminately slaughtered and ate humans.
As a last resort, the humans used nuclear weapons to drive back the monsters.
This day where these incidents occurred at the same time around the world
was remembered as "Judgment Day".
The monsters were called "Magna"
50 years have passed, and the Magna have disappeared
and the fear became something of the past.