Utilizing Professor Yuuko Kouzuki's technology and Kasumi Yashiro's psychic abilities, Cadet Takeru Shirogane is transported back to his original world. With a pressing mission ahead, Takeru seeks Yuuko's aid in his realm to advance the critical Alternative IV project—a final beacon of hope for humanity in their war against the invading alien race known as the BETA. As the decisive anti-BETA initiative reaches its climax, Takeru and fellow cadets successfully graduate from the Yokohama pilot training academy. Yet, a harrowing event unfolds during the testing of a new operating system for the Tactical Surface Fighters, the towering combat mechs utilized in the battle against the BETA, as Takeru and his team are ambushed by the relentless foes. Escaping by a thread, Takeru grapples with the haunting loss of a dear comrade, plunging him into a profound state of trauma and despair. Overwhelmed by the horrors he witnessed, Takeru retreats to the alternate world, only to encounter a parallel tragedy. According to Yuuko's hypothesis, individuals across parallel dimensions are destined to face analogous trials. Thus, Takeru must confront his inner demons and find the strength to fight on if he is to safeguard those he cherishes from a shared fate.