"Super Robot Wars Original Generation - The Animation" is a 12-episode OVA series that adapts elements from the "Super Robot Wars Original Generation" video game series, focusing on the conflict between Earth and extraterrestrial forces. The story is set in a world where humanity has developed advanced humanoid weapons known as Personal Troopers to combat alien threats. The narrative primarily revolves around the Earth Federation Army's Special Task Force, known as the ATX Team, and their efforts to protect Earth from the aggressive extraterrestrial race known as the Aerogaters.

The protagonist, Ryusei Date, is a young and skilled pilot who operates the Gespenst Mk-II, a prototype Personal Trooper. Alongside him is Kyosuke Nanbu, a calm and collected pilot who commands the Huckebein Mk-II, and Excellen Browning, a cheerful and sharp-witted pilot who operates the Alt Eisen. The trio forms the core of the ATX Team, working under the command of Lieutenant Colonel Lefina Enfield. Their mission is to defend Earth from the Aerogaters, who seek to conquer the planet using their advanced technology and powerful mechs known as Balmarian units.

The plot intensifies as the Aerogaters launch a full-scale invasion, deploying their elite forces and massive warships. The ATX Team faces numerous challenges, including internal conflicts within the Earth Federation, the mysterious origins of the Aerogaters, and the emergence of powerful new enemies. Key antagonists include Ingram Prisken, a former ally with a hidden agenda, and Bian Zoldark, a rogue scientist who seeks to use the conflict for his own purposes. The series explores themes of loyalty, sacrifice, and the ethical implications of advanced weaponry, as the characters grapple with the consequences of their actions in a war that threatens the survival of humanity.

The narrative also delves into the personal struggles of the main characters. Ryusei must confront his insecurities and grow as a leader, while Kyosuke and Excellen navigate their complex relationship and shared past. The series balances intense mecha battles with character-driven moments, providing a cohesive and engaging storyline. As the conflict escalates, the ATX Team uncovers deeper secrets about the Aerogaters and their connection to Earth, leading to a climactic showdown that determines the fate of both worlds. The series concludes with a resolution that ties together the central plot threads while leaving room for future developments in the "Super Robot Wars" universe.