The fission yeast  Schizosaccharomyces japonicus , comprising  S. japonicus  var.  japonicus  and  S. japonicus  var.  versatilis  varieties, has unique characteristics such as striking hyphal growth not seen in other  Schizosaccharomyces  species; however, information on its diversity and evolution, in particular mating and sporulation, remains limited. Here we compared the growth and mating phenotypes of 17 wild strains of  S. japonicus , including eight  S. japonicus  var.  japonicus  strains newly isolated from an insect ( Drosophila ). Unlike existing wild strains isolated from fruits/plants, the strains isolated from  Drosophila  sporulated at high frequency even under nitrogen-abundant conditions. In addition, one of the strains from  Drosophila  was stained by iodine vapor, although the type strain of  S. japonicus  var.  japonicus  is not stained. Sequence analysis further showed that the nucleotide and amino acid sequences of pheromone-related genes have diversified among the eight strains from  Drosophila , suggesting crossing between  S. japonicus  cells of different genetic backgrounds occurs frequently in this insect. Much of yeast ecology remains unclear, but our findings suggest that insects such as  Drosophila  might be a good niche for mating and sporulation, and will provide a basis for the understanding of sporulation mechanisms via signal transduction, as well as the ecology and evolution of yeast.