The Jet is one of the unused sprites found in Metal Slug 5. The pilot of the Jet is similar to Rumi Aikawa, however that is unlikely because of the many differences in facial features. This Jet was meant to be deployed from the front of The Shooting Ray between the cockpits (as seen on the boss' concept art) and become the support enemy during the battle. But, since the game was rushed, so they ended up being scrapped.
The Jet is modeled after the German Messerschmitt Me 163 Komet.