Ostracod crustaceans are among the most abundant microfossils in the geological record, thanks to their strongly calcified shell. Most of the fossils belong to the suborder Cytherocopina, which also has a rich diversity of living species. Unfortunately, many of the living representatives are known only by their shell morphology. Soft body always provides valuable insights into the phylogeny, and sometimes conflicts with currently accepted systematics of this group. We provide a complete description of Coquimba ishizakii Yajima 1978, collected from Jeju Island, South Korea. This is the first report on soft body morphology for the entire genus Coquimba Ohmert 1968, and the first record of this genus from Korea. Its soft body morphology is similar to other representatives of the family Hemicytheridae, where Coquimba currently belongs. After reviewing all records of C. ishizakii, we propose that several of them belong to different species, such as all those from Taiwan (modern and fossil). We also provide 18S rRNA and 28S rRNA sequences for this species, the latter being reported for the first time for the entire family Hemicytheridae.