Our Last Crusade or the Rise of a New World (light novel)

A great war has raged for years between the scientifically advanced Empire and Nebulis, the realm of magical girls—until the youngest knight ever to receive the title of the Empire's strongest meets the princess of the rival nation. Though they are sworn enemies, the knight is taken by her beauty and dignity, and the princess is moved by his strength and way of life.

For years, a great war has raged on between the scientifically advanced Empire and a paradise of witches known as the Nebulis Sovereignty. This age-old battle sets the scene for a fateful encounter between two young combatants: an imperial swordsman, Iska, and the witch princess, Aliceliese. As sworn enemies, they vow to cut each other down in order to unite their worlds, and yet Iska finds himself entranced by her beauty and righteousness, while Aliceliese is moved by his strength and resolve. In the midst of a never-ending war that forbids them from being together, they have no choice but to destroy each other-or find another way.