I doubt it. I’m not sure there is a home demo of Behind The Mask because, in this case, Michael didn’t compose the music.
The more instrumentally complex demos (e.g. The Girl Is Mine demo, Beat It demo (the one
@AlwaysThere was talking about, not the home demo) and the other two Billie Jean demos that we know of) were all recorded at professional studios.
I believe this may be the case with Behind The Mask, unless there is a version where Michael is improvising a melody on top of the original instrumental by Yellow Magic Orchestra.