Kei and his childhood friend Minghua are Chinese refugees fleeing to Japan to escape an unknown and highly advanced alien force called the "Xi". Several Xi aircraft arrive and attack the ship Kei and Minghua are riding in, but they are saved by the intervention of a highly advanced plane resembling a JAS 39E/F Gripen. The Gripen crashes into the water after the Xi retreat, and Kei swims over to rescue the pilot, who is a mysterious girl that kisses him upon seeing him...