During World War II, Japan imported 150 South American nutria for military fur; after mass escapes and releases, their descendants spread across at least 19 prefectures and dug through rice fields and reservoir banks

During wartime, Japan imported nutria for their lucrative fur farming, which inadvertently gave rise to large invasive populations. Originally from South America, these semi-aquatic rodents escaped captivity and thrived in the wild. Their presence negatively impacts agriculture, particularly rice paddies and reservoir banks. As a result, Japanese law now prohibits the ownership and release of these animals.