He is found guarding the Stadium restrooms. He is armed with an M16A2assault rifle. He tells players to not loiter near the bathrooms and that there can't be groups of people gathering in front of the bathrooms and to do his/her business and return to the field. This will eliminate the risk of survivors forming groups and planning escapes. Not much else is known about him.
Strangely, even though he is an Army sergeant, his name is Private Ramirez. This is most likely an error by Con.
The character may be a reference to Private James Ramirez, one of the player characters in Call of Duty: Modern Warfare 2.