"Planet Robot Danguard Ace" is a science fiction mecha anime series set in a future where humanity faces a critical energy crisis. The story revolves around the discovery of a distant planet, Planet Promete, which holds vast reserves of energy resources essential for Earth's survival. To secure these resources, the Earth Federation establishes the Danguard Project, a mission to colonize and exploit Promete. However, the planet is already inhabited by a hostile alien race known as the Zuro, who fiercely resist human encroachment.

The protagonist, Takuma Ichimonji, is a young pilot whose father, Dr. Ichimonji, was a key scientist in the Danguard Project but mysteriously disappeared. Takuma joins the Danguard Ace team, a group of elite pilots operating advanced mecha called Danguard robots, designed to combat the Zuro and protect Earth's interests. The Danguard robots are equipped with cutting-edge technology, including the powerful "Danguard Cannon," which becomes a pivotal weapon in the conflict.

As the series progresses, Takuma uncovers secrets about his father's disappearance and the true nature of the Danguard Project. The narrative explores themes of loyalty, sacrifice, and the ethical implications of resource exploitation. The Zuro, initially portrayed as antagonists, are gradually revealed to have their own motivations and struggles, adding depth to the conflict. The series features intense mecha battles, strategic missions, and interpersonal drama among the Danguard Ace team members, including rivalries and alliances that shape their journey.

Key characters include Captain Dan, the stern but compassionate leader of the Danguard Ace team; Mii, a skilled pilot and Takuma's close ally; and Professor Yamanouchi, the chief engineer responsible for maintaining the Danguard robots. The series balances action-packed sequences with moments of character development, as the team grapples with the moral complexities of their mission and the personal stakes involved in their fight for survival. "Planet Robot Danguard Ace" is a classic example of 1970s mecha anime, blending futuristic technology with human drama and interstellar conflict.