Kimi to Boku no Saigo no Senjou, Aruiwa Sekai ga Hajimaru Seisen  

Our Last Crusade or the Rise of a New World, or Perhaps the Beginning of the World's Holy War, キミと僕の最後の戦場、あるいは世界が始まる聖戦, ศึกสุดท้ายของเธอกับผมคือจุดเริ่มต้นของโลกใบใหม่

Astral power is an energy that exists all around us and can be harnessed by astral mages. These individuals possess unique abilities and are feared by those in power due to their potential for destruction. The Empire seeks to control and suppress the use of astral power, leading to persecution against those who display it. As a result, a group of oppressed mages formed the Nebulis Sovereignty to escape from their tormentors. For over a century, these two nations have been at odds, with the war still raging today. In an effort to end the conflict, the Empire leadership has decided to release Iska, a talented knight who was imprisoned for committing a great crime. However, his freedom comes with a condition: he must hunt down and defeat the Ice Calamity Witch, a fearsome mage known for her destructive powers. Despite their differences, both Iska and the Ice Calamity Witch, Aliceliese "Alice" Lou Nebulis XI, share a desire for peace and an end to the war. Fate has brought these two individuals together, creating a bond that transcends mere coincidence as they work towards a common goal: a world without struggle, pain, or suffering.