The homunculus first appeared as a playable character in the off-kilter Guilty Gear Isuka before showing up in a couple of re-releases of GG XX and then disappearing.
Trailer: https://www.youtube.com/watch?v=ZjqfSOnuyyM
GG Strive on FAB: http://www.fightabase.com/gamesMain.aspx?id=1194&sId=26
nice