During the Gryps Conflict in UC0087 the AEUG relied heavily on mobile suits stolen from the Earth Federation, mainly the RGM-79R GM II. However its leadership soon decided that the AEUG needed a mass-produced unit of their own so that they could beat the Titan’s suits. The task to develop this new suits went to Anaheim Electronics, which then introduced the Nemo. Although this new suit strongly resembled the old GM II it was far better in terms of generator power, thruster acceleration and maneuverability. Also, the Nemo was able to use already existing weapons like the RMS-099 Rick Dias’ beam saber or the GM II’s beam rifle, which also reduced the costs to produce this unit. The Nemo quickly proved to be a powerful unit and was thus used in several important battles like the attack on Jaburo.
The Nemo eventually developed into new MSA-004 (MSK-004) Nemo II. There is no information available for it, however. The design of Nemo II also developed into MSA-004K (MSK-004K) Nemo III, armed with an addition shoulder beam cannon to allow it to take the role of a medium range support unit. Still, the Nemo III never passed the prototype stage and it wasn't mass-produced.
The design of Nemo also inspired another of Anaheim Electronics's mass production mobile suit, the MSA-007 Nero.