Kawahara's series has also been adapted as a collection of six light novels written by and illustrated by Kazune Kawahara. They were published by Shueisha under its Cobalt imprint starting in June 2007.
- , published 28 June 2007 (ISBN 978-4-08-601047-4)
- , published 1 August 2007 (ISBN 978-4-08-601060-3)
- , published 1 November 2007 (ISBN 978-4-08-601097-9)
- , published 26 December 2007 (ISBN 978-4-08-601120-4)
- , published 1 April 2008 (ISBN 978-4-08-601154-9)
- , published 2 September 2008 (ISBN 978-4-08-601212-6) - This is an original story, and not an adaptation.