Sentai
It is a term used during World War II by the military of the Empire of Japan. Imperial Japanese Army (IJA) and Imperial Japanese Navy  (IJN) Air Service sentai units were equivalent to a group or wing in other air forces. However, the term had slightly different meanings in the IJA and the IJN. The Japanese navy sentai were squadrons of four ships (battleships and cruisers). Japanese submarines were also grouped in sentai.