Mehmet Merca holds the rank of Lieutenant JG in the Earth Federation's Cabinet Department 6 intelligence division. He commands the Mastema special forces unit under direct Federation government control. His primary mission involves investigating the remnants of the asteroid base Axis in the wake of the Laplace Incident, driven by Federation concerns over Psycho-frame technology. Mastema's objective is to locate and secure any related Axis research or intelligence.

Demonstrating pragmatic leadership, Merca recruits two civilians with past Zeon affiliations—engineer Arlette Almage and test pilot Danton Hyleg—for the Mastema expedition. His demeanor contrasts with typical military commanders, marked by a "soft fashion" and greater ease interacting with civilians than military officials, indicating adaptability in team dynamics. During the Axis operation, he coordinates Mastema's movements amidst unexpected attacks from the private militia Birnam and their Gundam AN-01 Tristan pilot, Quentin Fermo. Merca maintains focus on mission parameters despite escalating hostilities, keeping communication open with Arlette and Danton during combat.

Following the mission, Merca visits Arlette and Danton at their Side 6 laundry business, indicating a sustained connection to the civilians he recruited.