The Japanese sea lion (Zalophus japonicus) (Japanese: ニホンアシカ, romanized: Nihon ashika, Korean:강치,바다사자^[3]) was an aquatic mammal that became extinct in the 1970s. It was considered to be a subspecies of the related California sea lion (Z. californianus) until 2003. 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. They were hunted commercially in the 1900s, leading to their extinction.