Core resonance binds mech pilots and guardian angels on the battlefield among the stars. Stella, a Class A pilot, is betrayed and left for dead by Silas, the Class S Swan Angel who has been her partner for three years. Instead of breaking completely, she chooses Orion, a Class B Black Viper Angel burdened with a younger brother labeled "defective." What no one sees coming is Orion’s true identity—an SSS-Class war god—setting off a ruthless counterstrike that could change everything.