[2][3] In parallel to the twelve volumes, eleven standalone light novels of the series have also been published starting on December 17, 1998.
In January 2010, Gatoh wrote another of these stories in celebration of Gekkan Dragon Magazine's 300th issue.
Another, written by Naoto Ōguro and also illustrated by Shikidouji, was released from August 20, 2011 to February 20, 2016 consisting of thirteen volumes and is set years after the original series' ending.
[5] The light novels have also been adapted into various manga,[6] as well as four anime television series for which Gatoh was also part of the staff.
series for North America release, publishing the first regular light novel on September 11, 2007.