In the midst of a fierce war between the Katjvarna Empire and the Kioka Republic, Yatorishino, a member of a prestigious family, is determined to excel in the high-ranking officer exams. She persuades Ikuta, a carefree and womanizer, to assist her in exchange for a favor from her family. After a successful written test, they embark on a journey by boat for the next phase. However, their plans are derailed when the boat sinks, leaving Yatorishino, Ikuta, along with other examinees, and a significant, enigmatic young girl stranded deep within enemy territory.