Kei Amagi is a Japanese creator known for originating manga and light novel series, primarily active since the late 1980s. In addition to working as a writer, Amagi has a background as a manga artist and illustrator, with early works appearing in various publications starting in 1987. One of the earliest credited manga works is Stainless Night from 1994.

Amagi is best known as the original creator of the fantasy series Assassins Pride. The project began as a light novel series, with the first volume published in January 2016 by Fujimi Shobo under their Fujimi Fantasia Bunko imprint. The novels feature illustrations by Nino Ninomoto. The story, set in a world where noble families possess mana to fight monsters, follows an assassin tasked with tutoring a young noblewoman he may be ordered to kill if she lacks magical talent. The series received the Grand Prize at the 28th Fantasia Awards in 2015 prior to its publication.

The success of the light novel led to a manga adaptation illustrated by Yoshie Katō, which was serialized in Shueisha’s seinen magazine Ultra Jump from May 2017 to August 2022, compiled into ten tankōbon volumes. An anime television adaptation produced by EMT Squared aired from October to December 2019, spanning twelve episodes.

Beyond Assassins Pride, Amagi launched another light novel series, Aoi to Kowe no Rakuen Shoujo (tentatively translated as The Paradise Girl of Blue and Broken Wings), published by GA文库 in April 2021 as part of the imprint’s 15th-anniversary lineup.

In terms of artistic identity, Amagi has expressed a preference for narratives that twist established world settings and focus on the dynamics of relationships between characters. The creator has been noted as a long-time enthusiast of specific genres, with a career that spans several decades in the manga and light novel industries.