Nejimaki Seirei Senki - Tenkyou no Alderamin

The Katjvarna Empire is at war with the Kioka Republic, defending its borders against enemy attacks. Yatorishino, a young woman from an influential imperial family, is preparing for the high-ranking officer exams and persuades Ikuta—a lazy, anti-war womanizer—to take them with her in exchange for a favor from her family. After the pair pass the written test, they set out by boat for the next exam. When the vessel sinks, Yatorishino and Ikuta are stranded behind enemy lines alongside several other examinees and a mysterious little girl of great importance.