Fifteen volumes have been released as of September 2019. It was acquired by Micro Magazine, who published the first light novel volume in 2014. It was serialized online between 20 on the user-generated novel publishing website Shōsetsuka ni Narō. That Time I Got Reincarnated as a Slime (Japanese: 転生したらスライムだった件 Hepburn: Tensei Shitara Suraimu Datta Ken) is a Japanese fantasy light novel series written by Fuse, and illustrated by Mitz Vah.
