MF文庫J
, is a Japanese light novel series written by Reiji Kaitō and illustrated by Ruroo. Media Factory has published seventeen volumes under their MF Bunko J imprint from November 2009 to July 2017. A manga adaptation by Hakaru Takagi began serialization in Media Factory's "Monthly Comic Alive" magazine in 2010. A 12-episode anime television series adaptation aired in Japan between October 7 and December 23, 2013.