Alex K. Stewart, whose full name is Alex Kandley Stewart, is a young man of Mexican origin with black hair and gold eyes, and a lean, fit physique reflecting his athletic background. His life is defined by a deep love for baseball and a dream of becoming a professional player, inspired by watching major league games with his parents as a child. He is a right-handed thrower and left-handed batter. Born into poverty, he lost his mother at a young age and moved to his father's hometown in northern Mexico at seven. There he befriended Marcos E. Garcia and Sheila Levitt. By twelve, he worked as a paper boy earning meager wages. Driven by the hope of escaping poverty, achieving the American Dream, and pursuing baseball, he and Marcos left Mexico for the United States, eventually joining the Annex Project as a way to gain citizenship. Stewart is a member of Squad 2 on the mission to Mars. His key relationship is with Marcos, marked by both rivalry and deep loyalty; they often argue and fight but share an unbreakable bond. He also shares a significant past with Sheila, and their reunion is a pivotal moment. Stewart is defined by his passion for baseball, resilience from hardship, and care for his friends. He undergoes the M.O. Operation, granting him the characteristics of a Harpy Eagle. This gives him the ability to fly, eyesight eight times more acute than a human's, and immense upper body strength. He becomes a master of ranged combat, using specialized multi-gadget balls that can be bladed or explosive. His throwing accuracy and power allow him to strike targets from impossible distances, often before they detect him. He and Marcos have a unique combination attack where Stewart pitches these balls for Marcos to bat with his staff, increasing their speed and destructive force. Over time, Stewart evolves into a recognized soldier, becoming a member of the Sixth Division and later its leader, holding the number one position in the M.A.R.S. Ranking.