Grimoire of Zero (Japanese: ゼロから始める魔法の書, Hepburn: Zero kara Hajimeru Mahō no Sho, lit. "Starting the Magical Book from Zero") is a Japanese light novel series written by Kakeru Kobashiri and illustrated by Yoshinori Shizuma. The light novel won the Grand Prize at the 20th annual Dengeki Novel Awards. ASCII Media Works has published it in eleven volumes from February 2014 to December 10, 2017. The series has received a manga adaptation illustrated by Takashi Iwasaki. A spin-off manga series, Zero kara Hajimeru Mahō no Sho Nano! (ゼロから始める魔法の書なの) has also been published and illustrated by Yasuoka. An anime television series adaptation by White Fox aired between April 10, 2017 and June 26, 2017.

It is the year 526 of the Liturgical calendar. Witches and their sorcery are notorious throughout the land, though knowledge of the existence of magic remains elusive. A half-man, half-beast mercenary, his kind scorned by the populace, dreams day and night of becoming a human. However, his fateful encounter one day with a witch by the name of Zero turns his dreams into reality. She offers to turn him human if he will escort her as her guard on her search for a magical tome, one that possessed powerful knowledge which could wreak havoc in the wrong hands. The two begin their travels with this agreement binding them together, with the mercenary serving as Zero's protector, though he despises her kind.

Source: Wikipedia