When regular high school student Aoba Watase is targeted by a massive robot called a 'Valiancer,' his enigmatic classmate Hina Yumihara intervenes to save him. Revealing their time-travel origins, Hina thrusts Aoba 70 years ahead to prevent his impending demise. In this unfamiliar future, Aoba unexpectedly finds himself piloting the Valiancer 'Luxon' amidst a fierce battle between the Free Pact Alliance (FPA) and Zogilia Republic. Teaming up with skilled FPA pilot Dio Weinberg, Aoba undergoes a successful 'coupling,' enhancing their abilities through shared experiences. Despite surviving the intense combat, Aoba is apprehended by the FPA vessel Cygnus for questioning. While his primary worry is returning home, he soon discovers he is entangled in a world-saving conflict he never anticipated.