Genomic sequencing data and morphological properties demonstrate evolutionary relationships among groups of the fission yeast,  Schizosaccharomyces  Phylogenetically,  S. japonicus  is the furthest removed from other species of fission yeast. The basic characteristics of cell proliferation are shared among all fission yeast, including the process of binary fission during vegetative growth, conjugation and karyogamy with horsetail movement, mating-type switching, and sporulation. However,  S. japonicus  also exhibits characteristics that are unique to filamentous fungi.  S. japonicus  is a nonpathogenic yeast that exhibits dimorphism. Depending on the environmental conditions,  S. japonicus  transforms from yeast cells into filamentous cells (hyphae), and blue light triggers synchronous septation of hyphal cells. A rough version of the whole-genome sequence is now available, facilitating genetic manipulation of  S. japonicus.  Furthermore, the extensive genetic knowledge available for  S. pombe  is aiding the development of genetic tools for analyzing  S. japonicus. S. japonicus  will help shed light on the evolutionary relationships among the fission yeast.