Johnny Sasaki, nicknamed Akiba by his comrades in Rat Patrol Team 01, was a U.S. Army soldier, and sometimes mercenary, who participated in the Shadow Moses Incident, the Big Shell Incident and, more prominently, the events of Liquid Ocelot's Insurrection. His grandfather, also named Johnny, was encountered by Naked Snake during Operation Snake Eater.

During Liquid Ocelot's Insurrection, his entire body was often covered with wearable computers. Using a wrist-mounted keyboard and a goggle monitor, he specialized in scouting, patrolling, record keeping, data analysis, explosives, and traps. He became proficient in these areas in an attempt to match the skills of his nanomachine-enhanced teammates, though he would later admit that he never came close to doing so. Johnny suffered from irritable bowel syndrome and, due to his lack of nanomachines, also consumed local water without normal nanomachine filtration. This caused his diarrhea and cramps to become particularly bad during missions, although he seemed to blame the bouts of diarrhea on trying to hold up good-looking women during a mission.

Despite his poor hand-to-hand skills and generally hapless behavior, Johnny exhibited excellent firearms proficiency when he finally engaged in a gunfight with Liquid Ocelot's FROG troops (an earlier incident with the safety left on notwithstanding).