The Encounter of the Two Nations' Ultimate Weapons
Two nations, the Empire and the Nebulis Sovereignty, have been at war for 100 years. Imprisoned for freeing a witch, Iska is given a chance at freedom. In exchange, he must take down a powerful astral mage known as the "Ice Calamity Witch."
Aired 07/10/2020EP 1 - The Encounter of the Two Nations' Ultimate Weapons

2020
Our Last Crusade or the Rise of a New World
Embroiled in a hundred-year war, young Iska is sent to assassinate the Ice Calamity Witch, Aliceliese. Meant to murder each other, their initial encounter on the battleground creates doubt in their missions, but finding common ground together would make them traitors to their own countries. Though circumstances previously made them enemies, their now conflicted hearts may just make them lovers!
(Source: Funimation)