Yeah, I've been wandering around in a manga depository, and I found this gem.
It's about a young transfer student, and a fifth-grade exorcist.
The girl's the exorcist if you were wondering.
It's really a cute series, and the character designs are pretty nice(I swear, one of the ghosts looked like Akira from Devilman).
Anyways, the age progression is more of a before/after shot, but it's still nicely orchestrated. It's in the seventeenth chapter, called "The cursed Dress".
Also, the chapter called "bye bye baby", Don't get your hopes up for an age regression, it's just a little clinging baby ghost.
Here's a link to where you can find the downloads for the series(it's sadly incomplete) -
http://www.mangaworld.org/ [It's a java-based site, so I couldn't give a direct link]
And I'd supply a zip of the file, or a picture, but the uploaders not working for me today.