The planet has been embroiled in a brutal conflict with the BETA, extraterrestrial beings who descended upon Earth in 1973. Amidst the turmoil, Takeru Shirogane, a high school student, awakens from a terrifying nightmare wherein mankind has been defeated. His dream turns out to be a memory from an alternate universe where the Alternative V program was initiated, sending loads of people to space while leaving the billion survivors on Earth to suffer. Determined to prevent the dystopian future, Takeru enlists in a military camp at his old high school in Yokohama. He persuades Professor Yuuko Kouzuki, the vice-commander of the base and the head of the Alternative IV project, to halt Alternative V. Takeru and his comrades must learn to operate the colossal humanoid machines Tactical Surface Fighters (TSF) to ensure Alternative IV's success. But with only two months of training and his limited foreknowledge, Takeru races against time to prevent the impending tragedy.