Zero kara Hajimeru Mahou no Sho

In the year 526, humanity is well aware of witches and the feared art of sorcery they practice, yet the true study of magic remains entirely unknown. Amidst this world lives a mercenary who is half-man and half-beast—a member of a race humans mockingly refer to as "fallen beasts." He has spent his life longing to become fully human, but his fate shifts dramatically when he encounters a mysterious witch. Offering him exactly what he desires most, she proposes a simple bargain: if he wishes to take human form, he must serve as her bodyguard. Introducing herself only as Zero, the witch reveals that she is searching for a stolen grimoire known as The Book of Zero, which bandits recently plundered from her lair. This singular tome supposedly holds magical knowledge powerful enough to effortlessly bring the entire world to its knees. To achieve his lifelong dream, the mercenary has no choice but to accompany Zero on her quest, forcing him to travel alongside the very kind of sorceress he has always despised. Thus begins the unlikely journey of an arrogant witch and a gentle-hearted beast.