Ooya is an adult male salaryman who commands the giant robot Big Mighty, which he also primarily designed. His role shifts from conventional business to leading the robot's combat team. Initially operating under orders, his mission is to seek out and defeat giant robots worldwide, including the autonomous Junerin in Genes. His crew consists of engineer Honda, pilot Nakajima, and electronics specialist Matsushita.

Ooya exhibits reluctance toward violence, especially after observing Kana's protective relationship with Junerin. This leads to a failed attempt to defeat Junerin, prompting his superior Shimada to assume direct control of Big Mighty for a more aggressive confrontation.

Ooya later befriends Junerin's creator, Kana, bonding over their shared apprehensions about robotic warfare. This friendship fosters personal growth, leading Ooya to challenge his initial mission. His character arc concludes with a shift from antagonist to ally, supporting Kana during the climactic battle against Shimada's "perfect" robot.