Discovered this in another part of the forum but I figured since it is AP I would put it here.
The hentai from what I can see and find is about 4 little girls eat these cookies which ends up aging them up, though apparently they keep their same mindsets when aging up, Which is a bit questionable to me but process is process.
http://www.dlsite.com/ecchi-eng/work.../RE229081.html
Not completely sure if there's any shown process or that's just the way the trailer is edited, though the animation doesn't look great so I'm not 100% hopeful for it, but it looks like something. The title also implies that there's possibly going to be more of these in the future though again, I can find so little info on this outside of this website and the website that the trailer is linked from.
If anyone wants to spend 13 dollars on it you can do it, since I don't know how long it'll take for this to be put up on a hentai website.