This quirky Japanese PS1 game is about a princess or something who is turned into a toddler by a weird-looking alien, and her morphing ball friends who try to get her back to normal with some Arkanoid-esque gameplay. There's visible regression in the intro, looking like a Sailor Moon transformation, and every world completed makes the girl older until she's back to normal. The AP is all done in flashes, though.
5:22 (Toddler to 10 years)
11:05 (10 years to 13 years)
17:27 (13 years to 16 years)
29:10 (16 years to 18 years)