"Venus to Mamoru" is a science fiction anime series set in a futuristic world where humanity faces the threat of extinction due to the invasion of mysterious alien creatures known as the "Venus." The story centers around Mamoru Chino, a young man who becomes the pilot of a powerful humanoid weapon called the "Venus Fighter" after his hometown is destroyed by the Venus. This machine, designed to combat the alien threat, is humanity's last hope for survival.

Mamoru is joined by a group of skilled pilots and scientists who work together to protect Earth from the Venus. Among them is Aoi Minase, a determined and resourceful pilot who shares a close bond with Mamoru, and Professor Saionji, the brilliant scientist responsible for developing the Venus Fighter. As the series progresses, the team uncovers the true nature of the Venus, revealing a deeper connection between the aliens and humanity's past.

The narrative explores themes of survival, sacrifice, and the resilience of the human spirit in the face of overwhelming odds. Mamoru and his comrades face numerous challenges, both on the battlefield and within their own ranks, as they struggle to maintain hope and unity. The series balances intense mecha battles with moments of character development, delving into the personal struggles and motivations of each team member.

As the conflict escalates, Mamoru discovers that the Venus are not merely mindless invaders but possess a complex society and history of their own. This revelation forces him to question the morality of the war and the possibility of coexistence. The series builds toward a climactic confrontation that tests the limits of human ingenuity and determination, ultimately exploring whether peace can be achieved or if destruction is inevitable.