Yo guys, I found some AR in the manga
Dai Maou no OFF.
Don't quote me on this, but the manga apparently revolves around a young female Demon Lord, and in chapter 14, she wakes up as a baby because of some anti-aging drugs or something.
General info:
https://comic.pixiv.net/works/3572
The chapter:
https://comic.pixiv.net/viewer/stories/37777
No process, since she just wakes up that way, but we do get decent glimpses of her in oversized clothes, and it's pretty darn cute. The AR continues in the following chapters, though I couldn't tell how she returns to normal; a few single pages I found on Twitter (
https://twitter.com/_to_ti/status/95...792198/photo/1) imply she gradually but rapidly grows back to normal (a la Hare Guu), but I can't tell for sure.