Granulilimax fuscicornisMinato, 1989 is an endemic land slug of Japan. This slug was described as a member of the stylommatophoran family Philomycidae Gray, 1847, and subsequently transferred into the systellommatophoran family Rathouisiidae Heude, 1885. It is still unclear whether the taxonomic revision to Rathouisiidae is supported by genetic data. In this study, we investigated the phylogenetic position of the genus Granulilimax using G. fuscicornis and an undescribed species Granulilimax sp. Although the phylogenetic relationships between G. fuscicornis and rathouisiid slugs remain to be solved, our preliminary molecular analysis using mitochondrial COI and nuclear 18S genes strengthen the idea that the Japanese Granulilimax slugs belong to Systellommatophora.