21st Fleet Air Squadron (JMSDF)

Fleet Air Squadron 21 (第21航空隊) (which is also referred to as HS-21) is a unit in the Japanese Maritime Self-Defence Force. It is a part of the Fleet Air Force and comes under the authority of Fleet Air Wing 21. Equipped with Mitsubishi SH-60J & SH-60K anti-submarine helicopters, it is based at Tateyama Air Base in Chiba Prefecture.

Squadron structure
The squadron is composed of two flights:
 * 211th Flight is equipped with SH-60J and SH-60K helicopters
 * 212th flight is equipped with only SH-60K helicopters