Charles Carino is a skilled pilot—half-blood—serving in one of the two states engaged in a long, dragging aerial war. Once invented, the “metal hydride battery” that made it possible to refuel in the boundless ocean gave the people of both nations a way to reach each other—only for a reason for bloodshed to appear immediately afterward. One day, Charles receives a secret mission: piloting the newest reconnaissance amphibious aircraft “Santa Cruz,” he must cross 12,000 kilometers over the ocean alone, slip past the enemy blockade unnoticed, and deliver Fan del Moral—an innocent young aristocrat and future princess—straight to her fiancé, the heir prince of the Empire.