Terukuni Maru (照国丸) was a Japanese ocean liner owned by Nippon Yusen Kaisha (NYK). The ship was launched in 1929 by Mitsubishi Shipbuilding & Engineering Co. at Nagasaki, on the southern island of Kyūshū, Japan, entering service in 1930. She sank off the English coast in 1939 after striking a mine. Her sinking has been described as Japan's only World War II casualty outside East Asia before the 1941 attack on Pearl Harbor.