"Wolf Guy" by Hirai/Kadota is an adaptation of three episodes of the "Adult Wolf Guy Series" novels entitled "Tsuki to Yoru to Oogami" (月と夜と狼, vol.1), "Oogami wa Shinazu" (狼は死なず, vol.1) and "Jinrou, Akatsuki ni Shisu" (人狼、暁に死す, vol.5 [Kadokawa]). *Note!! : The "'Wolf Guy Series" novels originate from the two volumes manga that are also entitled "Wolf Guy" (Hirai/Sakaguchi).