 Wagahara originally entered the first novel in the series, originally titled , into ASCII Media Works' 17th Dengeki Novel Prize in 2010 and the novel won the Silver Prize.The first novel was published by ASCII Media Works on February 10, 2011, under their Dengeki Bunko imprint, and 20 main novels, two prequel novels, one spin-off novel, and three bonus novels have been released as of February 9, 2019.The final novel was initially scheduled to be published on July 10, 2020 but was later moved to August 7, 2020 due to the effects caused by COVID-19.