The Testament of Sister New Devil (Japanese: 新妹魔王の契約者テスタメント, Hepburn: Shinmai Maō no Tesutamento) is a Japanese light novel series written by Tetsuto Uesu and illustrated by Nekosuke Ōkuma. Thirteen volumes have been published by Kadokawa Shoten since 2012 under their Kadokawa Sneaker Bunko imprint. A manga adaptation has been serialized in Kadokawa Shoten's Shōnen Ace magazine since May 2013. A second manga adaptation has been serialized in Hakusensha's Young Animal Arashi magazine since February 2014. The first season of an anime television adaptation premiered on January 7, 2015.[7][8] The first OVA episode was released on June 22, 2015.[9] The second anime television season premiered on October 9, 2015. A second OVA episode was released on January 26, 2016.[10] A third OVA episode was released on March 28, 2018.[4][11][12]