Eisen Flügel (アイゼンフリューゲル, Aizenfuryūgeru) is a Japanese light novel series written by Gen Urobuchi and illustrated by Higashiguchi Chūō. The series was published in two volumes under Shogakukan's Gagaga Bunko light novel imprint from July to December 2009. The series was also adapted into a manga series illustrated by Anno Nanakamado, which was serialized from May 2016 to September 2018.