Tetsuo Akiyama, known as Captain Adams in the English dub, was the founding captain of the Earth Defense Army Far East branch's elite Science Guard Party (or Science Defense Squad). Tasked with leading this specialized unit investigating global mysteries and combating monster threats, Akiyama personally recruited every team member based on their exceptional scientific and military expertise, forging a highly competent force. He accepted the captaincy only after securing authorization for the team's exclusive use of the advanced Super Mardock aircraft, their mobile base and primary transport.

Akiyama led with consistent composure, seriousness, and intellectual focus. He approached missions with calm rationality, formulating swift strategies during crises while maintaining a collected demeanor. Beyond tactical command, he demonstrated attentive concern for his team's safety and well-being, fostering deep trust and earning recognition for his paternal presence—a contrast to his successor's brotherly style. Before commanding the Science Guard Party, Akiyama served as commander of the Earth Defense Army's Rescue Unit, where he formed a significant friendship with Daisuke Ogawara; Ogawara later resigned following the rejection of his proposed anti-monster weapon, Hector.

Akiyama's captaincy concluded after the battle against the monster Gibaaroga (Gibaruga) in episode 26. Under orders from the Earth Defense Army's Supreme Commander, he received a promotion and transfer to the United States branch to become Monster Combat Staff Officer. He bid a reluctant farewell as his team escorted his aircraft in their Bardy jets. Following this transfer, he did not reappear in the series. Captain Daisuke Gondo succeeded him.