Based on a Japanese light novel series written by Kazuha Kishimoto and illustrated by 40hara. It was serialized online between March 2015 and December 2016 on the user-generated novel publishing website Shosetsuka ni Narou, followed by nine epilogue chapters between February 2017 and October 2020. It was later acquired by Futabasha, who have published five volumes from October 2015 to July 2017 under their Monster Bunko imprint.