Zeon formed an Earth Attack Force and a ground force for ground control operations because the surface attack from orbit could not find a direct effect on the suppression of the main military bases of the Earth Federation Forces. The next Earth descent operation was carried out, and it was decided to obtain air superiority centered on the suppression base, but at the same time, in order to seize the command of the sea including the supply route, the Zeon Navy forces are a local area assuming underwater fighting as the main armored mobile weapon. Decided to develop a military mobile suit. The MS-06M was remodeled from the MS-06C as a test bed for developing a group of mobile suits for different purposes specialized in underwater operations. The design with a view to deep-sea work was expected to move to mass production as soon as possible, but in reality it does not reach the required performance due to the underwater resistance of the aircraft and the cooling problem of the main generator. Became clear. However, it continued to be used for the development of a small water flow engine equipped with a mobile suit and as a practical test machine for underwater fixed weapons. In line with the actual deployment of the MSM series, which is a specially designed aircraft, all seven aircraft produced were also assigned to the submarine fleet in each direction. The underwater armament sublock gun, which replaces the Zaku machine gun, was developed at the same time from the beginning, and fixed armament operated in the MSM series has been added after the actual battle deployment. Several aircraft captured by the Federal Army after the war have been operated by the Federal Army after repairing the control system.