ゼロの使い魔
"The Familiar of Zero" began as a series of light novels written by Noboru Yamaguchi and illustrated by Eiji Usatsuka under the original title "Zero no Tsukaima". Media Factory published 20 volumes in Japan between June 25, 2004 and February 25, 2011. Further publication was threatened by Yamaguchi's advanced cancer, which he died from on April 4, 2013, leaving the series unfinished. Yamaguchi had planned the series to end with 22 volumes. However, it was later decided by the publisher to continue the series in the author's absence, due in part to calls from fans to continue the series, as well as Yamaguchi's family wanting to see it completed. Yamaguchi had dictated the remaining plot of the series, including its ending, and entrusted it to the editors. Media Factory released volume 21 on February 25, 2016 and the final volume 22 on February 24, 2017. Seven Seas Entertainment licensed the series in 2007 under the title "Zero's Familiar", but later cancelled the release of the novels before releasing any.