電擊小說大獎
Originally, Narita entered the first novel into ASCII Media Works' ninth Dengeki Novel Prize in 2002 and the novel won the Gold Prize, placing third. The first novel was released in February 2003 under ASCII Media Works' "Dengeki Bunko" imprint, and as of December 8, 2012, nineteen novels have been released. In addition, one novel accompanied the first drama CD, released on March 31, 2006, and two gaiden novels were released in parts with DVDs of the anime adaption, released from October 24, 2007 to May 28, 2008. Daewon C.I. licensed the Korean-language release of the series in South Korea and releases the novels under their "Newtype Novels" imprint. A Chinese-language release in Taiwan and Hong Kong is licensed by the Taiwan branch of Kadokawa Media.