Regis Aurick, a hapless soldier with no skill in combat or horsemanship, lacks interest in his empire duties and immerses himself in books. Exiled to the borderlands, he crosses paths with Altina, also known as Fourth Princess Marie Quatre Argentina de Belgaria, a spirited young woman with striking red hair and ruby eyes. Recognizing Regis for his strategic acumen, Altina offers him the role of her tactician to help her reform the war-driven empire, wielding the fabled Grand Tonnerre Quatre sword. Despite facing doubt and skepticism from her peers, Altina remains determined to showcase her capabilities alongside her new tactician, challenging the status quo and risking it all. This is a narrative of warfare, romance, and political intrigue, blending the worlds of a scholarly soldier and a sword-wielding princess.