In the year 526 of the Liturgical Calendar, the existence of witches was widely known for their sorcery, yet the world remained ignorant of magic's intricacies. Our tale revolves around a mercenary who is part human, part beast, scornfully labeled as 'fallen beasts' by humans. Longing to shed his beastly form, his life takes a drastic turn when he encounters a witch named 'Zero'. Offering him a chance at humanity, Zero, a proud sorceress, enlists the mercenary as her protector in exchange for transforming him. Tasked with recovering a powerful tome stolen by thieves from her sanctuary, known as 'The Book of Zero', said to hold the key to dominating the world effortlessly. Despite his disdain for witches, the mercenary embarks on a journey with Zero, forging an unlikely partnership between a proud sorceress and a compassionate beast.