Yo guys, it turns out the manga
Kamichama Karin Chu had another AR than the one I had already posted about, in its third chapter.
Basically, a magical watch causes Karin and two guys to turn into toddlers; I also think Suzune was affected, but it's hard to tell since he was so small and young to begin with. It's poof-style, but it's adorable and does leave them in oversized clothes.
I only included a couple relevant pages in the attachments, but the rest of the chapter can be read here:
http://www.mangahere.cc/manga/kamich..._chu/v01/c003/