I hate family tie-ins with stuff like this, KH won't do family stuff, it's obviously nnot Riku
So the possibilities are
or DS (probably not him though)
You leave ouy the possibility of a new character.
one thing I noticed in th picture.
The shadow of the mystery character is not comlplete. it looks like it cuts off at mid leg.
Just this section of the mystery characters shadow is the same length of the entire shadow of VEN. This means that the mystery character is taller than ven. If there was a comparison chart of the different possiblities for characters we could probably eliminate a few things