The prototype Numan, Neifirst is responsible for controlling the Climate Control system on Motavia, as well as producing the Biomonsters that plagued that world. Her motivations were simple: People tried to kill her, she kills people back.
As a dueller, her battle plan is largely the same as Nei: Hit things over and over again really fast until they die. This seems to be a fairly effective plan, as she managed to defeat the hero of the first Shining Force before falling, her first time in.
She's still looking for her pink lace nightgown, though.