You play Sanjuro Makabe, a Mobile Combat Armor (MCA) pilot and Commander in the UCA Security Force. The UCA was originally formed by three dominant megacorporations (Andra Biomechanics, Armacham Technology Corporation, and Shogo Industries). Originally intended as a joint venture that would ensure the continued profitability of the three organizations that founded it, the UCA is now independent, and the dominant military power in existence.