Japanese Sea Lion (Zalophus japonicus) is thought to have become extinct in the 1950s.
Prior to 2003 it was considered to be a subspecies of California Sea Lion as Zalophus californianus japonicus. However, it was subsequently reclassified as a separate species. Some taxonomists still consider it as a subspecies of the California Sea Lion. It has been argued that japonicus, californianus, and wollenbaeki are distinct species because of their distant habitation areas and behavioral differences.
They inhabited the Sea of Japan, especially around the coastal areas of the Japanese Archipelago and the Korean Peninsula. They generally bred on sandy beaches which were open and flat, but sometimes in rocky areas.
Currently, several stuffed specimens can be found in Japan and the National Museum of Natural History, Leiden, the Netherlands brought by Philipp Franz von Siebold.The British Museum possesses a pelt and 4 skull specimens.