OCU army members Sakata, Lloyd, and his fiancée Karen entered a place prohibited by the USN. Driscol, a USN officer, caught them, and he killed Karen. Sakata and Lloyd were discharged for breaking the treaty and for starting a war between the OCU and UNS. Later, Gen. Olson hired them as mercenaries for a special mission, and Lloyd now seeks revenge for his loved one.
This game is also known as Front Mission 1st in Japan.