Hira Yakunin Yatte 1500-nen, Maō no Chikara de Daijin ni Sarechaimashita

Hira Yakunin Yatte 1500-nen, Maō no Chikara de Daijin ni Sarechaimashita is a spin off light novel in the I've Been Killing Slimes for 300 Years and Maxed Out My Level series.