The series is a collection of Japanese light novels by Masashi Okita, with illustrations by Unaji. The series started with the release of the first volume in August 2006 titled , and as of January 2011, 12 volumes have been published by ASCII Media Works under their Dengeki Bunko imprint. A manga adaptation by Kurumi Suzushiro started serialization in the April 2010 issue of ASCII Media Works' shonen manga magazine Dengeki Daioh. A 12-episode TV anime adaptation aired in Japan between July 1 and September 16, 2010, and has been licensed by Funimation Entertainment.