Shiden Kanzaki is a Japanese novelist and the original creator behind the manga and anime series Black Bullet. Born in Hokkaido Prefecture in 1985 and later residing in Tokyo, Kanzaki began his professional writing career in 2007. That year, he won the first Shogakukan Light Novel Award in the Gagaga Bunko category for his debut work, Marginal, also known as Critical Kill, which was published with illustrations by kyo.

Kanzaki is best known for creating the Black Bullet series. The story is set in a post-apocalyptic world where a viral parasite turns humans into monstrous creatures called Gastrea. The narrative follows Rentaro Satomi, a high school student who works as a civil security agent, and his partner Enju Aihara, a young girl infected with the virus who possesses superhuman abilities. The original Black Bullet light novels are written by Kanzaki and illustrated by Saki Ukai. The series began publication under the Dengeki Bunko imprint of ASCII Media Works on July 10, 2011. The light novel series concluded its initial run on April 10, 2014, with the release of its seventh volume, and reportedly achieved cumulative sales of approximately 950,000 copies.

The commercial success of the light novels led to multiple adaptations for which Kanzaki is credited as the original author. A manga adaptation, written by Shiden Kanzaki and illustrated by Hon Morino, was serialized in ASCII Media Works' Dengeki Maoh magazine from August 27, 2012, concluding in June 2014. The manga was compiled into four volumes. A thirteen-episode anime television series adaptation produced by the studios Kinema Citrus and Orange was announced in October 2013 and aired from April 8 to July 1, 2014. The anime was directed by Masayuki Kojima, with Tatsuhiko Urahata handling the script.

Following the release of the seventh volume of Black Bullet in April 2014, Shiden Kanzaki effectively ceased publishing new work and withdrew from public view. The series entered a long-term hiatus, and the author himself became known for his absence from the literary and convention scenes. Various unconfirmed theories have circulated within reader communities to explain his disappearance, including speculation about personal health issues or that he retired after finding financial success in stock trading. His earlier works include the light novel Koi no Cupid wa Handgun o Buppanasu, published in 2011. Shiden Kanzaki's writing is characterized by dark, gritty narratives that combine science fiction, action, and tragedy with an often cynical or harsh view of society. His works explore themes of survival, the burden of power, and discrimination against marginalized groups, such as the cursed children in Black Bullet. Despite his short period of activity, his works, particularly Black Bullet, have maintained a lasting cult following and are recognized for their significant influence on the dark science fiction and post-apocalyptic subgenres within Japanese light novels and anime.