Saikyou Shugosha to Eichi no Madou Hime: Shinigami no Chikara wo Motsu Shounen wa Subete wo Houmuri Saru

The Brugel Kingdom, famous for its vast libraries, houses the Forbidden Library in its capital, where dangerous and cursed texts are kept. Kumura, the Chief Librarian with all-knowing abilities, and Vil, the Assistant Librarian who can kill anything, are tasked with protecting these books. When the seal of a forbidden book is suddenly broken, a giant cloaked in mist emerges. Vil fights the creature using their Grim Reaper power to reseal it. Soon after, Vil is approached by a hostile empire seeking their power and is attacked for refusing. Kumura becomes a target in the process, prompting Vil to activate their true power in response.