"Armored Trooper Votoms: Big Battle" is a four-episode OVA series set in the "Armored Trooper Votoms" universe, serving as a direct sequel to the original 1983 television series. The story takes place on the planet Melkia, where the Gilgamesh Confederation and the Balarant Union continue their prolonged conflict. Chirico Cuvie, the protagonist, is drawn back into the fray after attempting to live a quiet life. Chirico’s past as a skilled Armored Trooper pilot and his connection to the mysterious Perfect Soldier program make him a target for both factions.

The narrative centers on Chirico’s involvement in a high-stakes battle over a powerful new weapon known as the "Diving Beetle," a highly advanced Armored Trooper capable of shifting between land and air combat. The Gilgamesh military, led by Colonel Rochina, seeks to secure the Diving Beetle to gain an edge in the war, while the Balarant Union aims to destroy it to prevent their enemy’s advantage. Chirico, caught in the middle, is forced to confront his past and his role in the ongoing conflict.

Throughout the series, Chirico allies with a group of mercenaries, including familiar faces like Vanilla and Gotho, as well as new characters like Fyana, a former Perfect Soldier with whom Chirico shares a deep connection. The group navigates treacherous battles, political intrigue, and personal vendettas as they attempt to prevent the Diving Beetle from falling into the wrong hands. The story explores themes of loyalty, the cost of war, and the search for identity, all while maintaining the gritty, militaristic tone characteristic of the "Votoms" franchise.

The OVA culminates in a climactic battle where Chirico and his allies face off against both Gilgamesh and Balarant forces. The resolution underscores Chirico’s enduring struggle to find peace in a war-torn world, leaving his ultimate fate ambiguous but reinforcing his status as a legendary figure in the "Votoms" universe. The series expands on the lore of the original show while delivering intense mecha action and character-driven drama.